Come and meet Those dancing feet On the avenue I'm taking you to 42nd Street

Nine p.m. Wednesday. Rehearsal Hall 4 of the Kennedy Center. Gower Champion's eyes are hidden behind sunglasses as he walks across the broad floor, crossing elaborate patterns in tape left from rehearsals of previous theatrical gestations there.

On the right, an 80-foot-long mirror reflects his passage. It also reflects 40 young dancers lounging in studious disarray in rows of folding chairs. Tammy Grimes and Jerry Orbach, Champion's featured players, converse calmly in a corner.

Strewn across the front of the brightly lit room are 23 musicians, mostly brass players, framed at one end by a harp and at the other end by a percussionist who adjusts his set of chimes.

Champion weaves among them to reach John Lesko, the musical director, and positions himself behind him. Lesko has the air of a man with a lot to do and not much time to do it in. He gestures, and the horn players bring their mouthpieces close and take a breath. The dancers are up and in position. It is a large room, made larger by the bright lights and long mirror.

In a moment there will be a burst of brassy sound, and the floor will shudder, and something will begin to come alive. Something conceived two years ago, and now very near birth. It is a new American musical called "42nd Street." It could be not only a comeback for some fine old tunes, but for Gower Champion, too.

Lesko nods and the room fills with music, voices, dancing: We're in the money, We're in the money, We've got a lot of what it takes To get along . . .

The familar song, written for the Busby Berkeley movie "Golddiggers of 1933," fills the hall only for a moment, before John Lesko stops his players. 1

"It's an eighth note," he says. "By UP be da da. By UP de da da. Make it an eighth note." The players reach toward their scores with pencils. mChampion says nothing.

The dancers stand around, glowing with . . . anticipation. They are dressed informally, but it is a careful informality. That is the sense of the event. The singers intend to sing at half-strength, saving their voices. The dancers have no taps on their shoes yet. The orchestra knows Lesko will stop them in mid-phrase again and again.

It is only a rehearsal, but it has some of the excitement of an opening, which in one respect it is: For the first time, the dancers, and the orchestra, and the featured players, and the director and choreographer are seeing everything they have worked on individually these past months come together for the first time. Previously, dancers and singers have worked in separate rooms on a New York rehearsal hall, to the accompaniment of piano music. This it their first taste of what the show will really sound like -- and feel like.

The result, whether they like it or not, is going to open Tuesday night in the Opera House.

The David Merrick organization has sunk a bundle into this Depression-era story of a theatrical troupe determined to put on their show against all the odds. It is based on the novel by Bradford Rope, and on the Busby Berkeley movie of 1933, starring Dick Powell, Warner Baxter, Ginger Rogers and Ruby Keeler. The film was, in fact, the origin of the cliche: Hard-working director finds production going down the drain when the star twists her ankle. Can a replacement be found? That film had four songs. This "42nd Street," which goes directly to New York's Winter Garden Theater after its five-week run here, has 16.

The orchestra moves on to "You're Getting to Be a Habit With Me," a song first written to the "42nd Street" movie by Harry Warren and Al Dubin, who still get credit for all the times here.

Tammy Grimes and Lee Roy Neams, who have a duet, move up to the piano and run through their parts sotto voce, adjusting to the orchestration, Champion chews on his sunglasses a few feet away. Grimes and Neams do a slow turn on the floor, walking through their dance numbers.

"Okay, this includes everybody," calls Lesko, as his musicians turn to "Dames," a song borrowed from the 1930s musical of that names."Dames" is to be a big production. The orchestra springs to life with vigor, filling the bright room with sound and sending 40 dancers through the steps Champion had devised for them weeks before, in another rehearsal space in New York City.

Those previous weeks of rehearsal were with piano only, however; now they were hoofing for the first time aganst the power of real instruments, and a real orchestration. The dancing went on and on. Lesko did not interrupt, and his players strained to keep up with the flashing spots on their pages. The first shine of perspiration broke out on the foreheads and shoulders of the dancers.

Champion had his sunglasses in his hand, and he was standing up.

The production number stopped with a jolt, leaving dancers stranded all over the floor. For an instant there was only panting. But the dancers for the first time could see Champion's eyes.A grin the size of a piano keyboard had spread across his face.

"That was lovely," he said.

There was an instant roar of applause from the entire company.

"Ten-minute break," Lesko said.

Gower Champion is 59 now. As a matter of fact, today is his birthday. He and Marge, his wife and partner, made their dancing debut at the Plaza Hotel in 1947, and in the 1950s appeared in several movies, among them "Show Boat" and "Lovely to Look At." They seemed to be on television every night. But Gower Champion really found his place on Broadway in the 1960s, where as a director he had a series of hits that included "Hello Dolly," "Bye, Bye, Birdie" and "I Do, I Do." He and Marge divorced in 1972, about the time Champion was trying to break iinto film directing.

"What do you think?" he asked rhetorically Wednesday night as the cast took its break. "You know, this is an exciting time -- it's the first look at what we've been working on, all put together. It's the first time anyone has even heard the orchestrations."

Champion confirmed that the 1933 movie and the novel by Rope were both used as sources for his show. "But this is not -- emphatically not -- a revival," he said, pulling on a cigarette. "It's not 'The King and I' or 'No, No, Nanette.' It's a new musical. I wouldn't have done a revival."

Champion was reminded that he had spoken up, in the late 1960s, to say that he was pessimistic about the future for American musical theater.

"Yes, well, that was right after the explosion of pop music, which seemed very healthy, but never really made it to the Broadway stage for some reason. Only 'Godspell' and 'Hair' and a few others adopted it. It was a huge loss for Broadway not to be involved in something that big."

Champion made a stab at becoming a movie director, with "Carnival" and a Debbie Reynolds vehicle called "My Six Loves," but neither is well remembered.

"The two movies were sort of flops," Chamapion said. "I made a decision to change everything. I had a place in Malibu Beach and was sort of a beach bum, and I got divorced, and I finally moved to New York and opted for Broadway. That's my world, I found out. Broadway is what I do."

He and Marge, who has remarried, have two sons -- aged 24 and 11 -- and so they see each other periodically. "That's about the extent of the relationship," he said.

Champion's hair is gray nowadays, and he has a stern countenance. He has never been much for nonsense anyhow. When they asked him to direct the 1969 Academy Awards show, he announced he was cutting out all the lame jokes he starlets, removed Bob Hope from the program, and insisted that it end on time.

"Places!"

In the "42nd Street" of 1933, it was Ruby Keeler who came to the rescue of the ailing show. In this production it is Wanda Richert, a newcomer. Her name appears on the program quite a way down from Tammy Grimes; however, Richert's name is in a box.

She came out in the middle of the floor for a duet with Jerry Orbach, in which she is to be persuaded by the company to save them from their twisted-ankle predicament.Not a bad role for a newcomer, eh?

"Jerry Orbach and Wanda Richert, please," called Lesko.

Richert, slim in her jeans and hands on her hips, looked Lesko in the eye over the heads of his musicians. He had pronounced it "Rye-chert."

"It's Rich-ert," she said -- as in rich, as in richer.

"Sorry," said Lesko, looking up with only one eye.

"That's all right," said Richert.

Music resounded again, and the dancers moved through their paces in the new, fully orchestrated scale, enjoying themselves. They ran through a crucial scene three or four times, and one by one the sotto voces gave way to full voice, and the walk-through dance routines to ebullience and spring. Three or four times Richert accepted the challenge called for in the script, three or four times the cast applauded and whooped -- as called for in the script -- and each time the whoops got a little louder.

Champion had his sunglasses off again.

By the time "Lullaby of Broadway" came up -- familiar from the Berkeley movie "Golddiggers of 1933" -- the runthrough was rolling as if it were opening night -- though the only audience was in the long mirror. The dancers wore a wide selection of footwear, from Frye boots to pumps to Adidas running shoes, but one thing nobody had on was taps -- the little Capezio Teletone taps that can turn a stage-full of thumping tootsies into a wall of rhythmic sound.

Even so, the floor commenced to shake, and it shook even harder under the assault of "42nd Street," the fast-moving title song. That song, the basis of the Kennedy Center's radio ad campaign, has already sold a lot of tickets for this run. (The ad wasn't performed by the company, whose own fully orchestrated version was heard for the first time only Wednesday night.)

By 11:30, the rehearsal was over, Lesko had stopped the action dozens of times, polishing entrances, correcting scores and marking places where he, orchestrator Philip J. Lang, and dance-arranger Donald Johnston had work to do. The dancers grabbed their towels and pocketbooks and walked out, pleased with something. Possibly with themselves.

"When do you know for sure if it's working?" somebody asked Champion.

"About the fifth performance," he said. "Opening night is always a mess, one way or another. But after the fifth night, I'll know."

Tammy Grimes, lighting a Kool in the hallway: "It's fallen together rather quickly, I think. The book is lean and precise, and the whole show has a nice, almost stark feeling.There's no sentimentality. Gower told us to remember that it's all taking place during the Depression. That the people in the show really are desperate for a success. Someone complains, and he's told -- 'If you don't like it, there's a breadline across the street.' But it's never very hard, in the theater, to feel that desperation anyhow."

Jerry Orbach, bounding down the hall: "Hey, you realize this show is going to have people humming the songs on their way in, as well on their way out?"

Carole Cooke, who plays one of the producers: "Hey, do you know why this show going to last? Because it's a real story. It not just dances and songs tossed together."

The 23 musicians cleared out too, their harpist struggling to keep up. In the backstage elevator, the wheels of her harp case got stuck for a moment. "That's the trouble with harpists," a horn player said. The "42nd Street" orchestra is almost all brass.

By midnight the big room was dark again. The sounds and dialogue and energy and months of preparation that came together there for the first time last week will be revealed Tuesday night in the Opera House. There will be taps on the shoes and Theoni V. Aldredge costumes. The 12 truckloads of sets will be in place and the lighting installed. And the critics will get their chance to pronounce it a staggering, top-tapping hit or a giant, overblown floppola, or anything in between.

And some other troupe, trailing script books and months of preparation, will set up in Rehearsal Hall to perform their backstage drama: the real one, the one the critics never get to see.