Ron Richardson has waited patiently for his overnight success.

"Yeah, 20 years to instant stardom," laughs the winner of the 1985 Tony for best supporting actor in the all-American musical "Big River," now docked at the Kennedy Center.

It's 1:30 in the afternoon, the working actor's crack of dawn, and Richardson is slowly warming up with a stream of black coffee and cigarettes.

"I got a call from my agent, who said, 'Ron, I have an audition for you.' And I asked what it was, and he said, 'Huckleberry Finn.' I just said, 'Oh.' " He laughs, savoring his oft-told I-almost-blew-it tale. "See, it was right in the middle of that controversy about Twain and the 100th anniversary and there had been so much publicity about the book."

Then out of work, he signed on despite his apprehensions about playing a runaway slave called Nigger Jim, from a book being burned and called "racist" by school groups. But the show has turned out to be a river of big returns. In the treatment by writer William Hauptman, composer Roger Miller and director Des McAnuff, it remains Huck Finn's story, but Richardson is undeniably its star, with his rich, liberating baritone and big, honest acting style.

Even though he received at least five copies of "Huckleberry Finn" as opening-night gifts, Richardson says he has yet to read it. "I made a decision once I got the role -- after six auditions -- that it would be best if I didn't read it till after I'd finished the role, because I didn't want it to affect what my thinking about the character was or what Des and Roger were trying to accomplish."

Instead, he drew some of his impressions of Jim from the memory of his grandfather, Wade C. Ellison, to whom he dedicates his nightly performances. "My Jim is very much like my grandfather, who was very proud and very noble and a great influence on my life. I'd spend summers with him at his farm in New Jersey and we'd do very Huck Finn-esque sorts of things -- fishing and crabbing."

It's clear that Richardson has found his character's strength and dignity. "Jim is an incredible survivor," he says, "a very moral man with a mission, and that mission was to free his family. I think that there was a genuine love for Huck. It's very difficult not to love a child, especially when you can see the child is very naive and innocent about a society which you've seen the underbelly of -- which Jim had seen the underbelly of.

"So in a way, the character's not so far removed from my own life. I can go only two generations back to my grandfather, who was born shortly after slavery -- his father was a slave. My father was a sharecropper. So I remember hearing many stories about what life was like in the South. In 50 years, our country has made incredible change, but not nearly as much as it should have made. I've dealt with racism and I've dealt with having opportunities taken away from me. There are very few jobs available to me now, as a Tony Award-winning actor, because there just aren't a lot of black roles around."

Richardson grew up listening to black spirituals at home and in church, and started singing them "as soon as I could open my mouth." His first memory of singing in public is in the Community Baptist Church Choir in Philadelphia. "Mrs. Watson was the organist at our church, and my voice was just ringing out over everyone else's in the children's choir. One day I just really got into it," he laughs. "I didn't sound like a boy soprano, I sounded like a coloratura, very high and light. My voice didn't change till I was 16 years old, and that summer I grew a foot. I left school in 10th grade as a soprano and came back that fall as a baritone."

His three-octave range and stylistic versatility -- integrating the styles of Dietrich Fischer-Dieskau, Sam Cooke and Arthur Prysock, among others -- took him from Philadelphia's All-City Boys' Choir and opera workshops through dinner theater and a stint as staff writer, artist and producer at Philadelphia International Records. In the late '70s he had a disco hit on that label with "Love Is Everywhere," as part of City Limits. Since then he's played the Chief of Police in "Timbuktu!" on Broadway, Sportin' Life in the Houston Grand Opera production of "Porgy and Bess," and James Thunder Early in "Dreamgirls."

And now, "Big River." Richardson says he's grateful to first-time musical composer Miller, who gave him unprecedented liberty in his interpretations of the songs. "Roger would say, 'Here's my music -- sing it.' Now, how often do you hear composers say that? . . . Composers can be real sticklers about every note and about interpolation or ad-libbing, but Roger encouraged it, because I think we have a similar understanding about folk music. Folk music has to be fresh every time. It's re-created every time you sing it, and that gives you a way to communicate emotion."

For Richardson, home is an apartment in Mount Vernon, N.Y., in a building that also houses his parents, brother and sister-in-law, and nephew Alvie ("the joy of my life"). "We can run from apartment to apartment," he says. "It's very nice to have my whole family there, especially throughout this upheaval. I like having a normal life -- I do eight shows a week, it's just that I work when everybody else plays."

"Big River" will roll along at the Kennedy Center through May 24, but the remainder of the national tour has foundered. Richardson, however, is prepared for adversity. He's talking about updating the 1949 Kurt Weill-Maxwell Anderson musical "Lost in the Stars," with its timely theme of a black man's impotence against South African justice, and "hoping to do a film, a mini-series, about the life of Nat King Cole. I'm talking to Cole's daughter Natalie Cole, as we speak, about playing her own mother."

He's also shaping a project on the Roberta Martin Singers, an influential gospel group of the '40s, which may become a revue or a full-fledged book musical. And he's toying with a dream of releasing a self-produced album by direct mail to the public. "That way I can do the music I want to do, a mishmash of everything -- the great songs and my original songs."

"Sure, it's difficult finding roles, but I've had a unique opportunity to be spotlighted as a major singer who can handle classical or sing pop. So I think when a role comes down the pike, I'll be one that producers will consider . . .

"But I'm gonna be busy anyway," he says, laughing an unworried, satisfied, very musical laugh.