"Timbuktu" is lushly lavish to look at but fairly interminable to endure. Director - choreographer - costumer Geoffrey Holder has referred to his followup to "The Wiz," as "a fairytale, a fable." Those who never have been a lush stage musical probably will be goggle-eyed, but those who've seen a half-dozen topflight ones might be more amused at solitaire. It will be at the Opera House through Feb. 5.

Saturday night's official opening found the very able Ira Hawkins replacing William Marshall as one of the four stars (the others Melba Moore, Eartha Kitt and Gilbert Price). They are an exceptional lineup of superior performers. To them, add a large, supporting cast of impressive shapes, sizes and grace.

"Timbuktu!" is a variation on the popular, 25-year-old musical, "Kismet." "Kismet." Middle East setting now has become Timbuktu, the rich, 11th-century remote, city of West Africa. Robert Wright and George Forrest wrote their "Kismet" score on themes from Russia's Alexander Borodin. To these they have added strains of African folk music, though only four new numbers replace several more dropped from the 1953 version. The story stems from a 1911 play which served Otis Skinner for a decade on stage and screen.

With so proven a record, there's nothing really wrong with giving this international warhorse another run down the track. But Timbuktu and the nation of Mali as a setting add little except inspiration to Holder as costumer.

Being a visual artist passionately in love with sunshine, Holder makes no pretense of recreating clothes that once dotted the alleys of Mali. Instead, his imagination conjures up materials, colors, shapes and lines which wealthy Arabs might now gather up during whirlwind tours of NeimanMarcus, Harrod's, Saks Fifth Avenue and Galaries Lafayette. He has employed the labors of millions of silkworms, heaps of bird feathers, mineral chips and tons of dyes. You get to thinking of those gay and gaudy "Folies-Bergere" revues and their mindless glitter.

Unfortunately, Tony Straiges has not been ingenious enough with his state design. He has avoided steps or stages in favor of a gentle, sandy-looking slope, and he hampers potentially sensational entrances with full-looking flats that necessitate entrances and exits within a constricted space. Thus when Kitt, elegant in white, makes her first entrance, she has rather a squeeze to get on at stage left, as do others. These technical failings often slow the pace considerably.

And pace plus clarity are needed in this tale of a storyteller-conman, Haji (Hawkins), who marries off his daughter (Moore) to a title and, through luck and guile, gets a rich widow (Kitt) for himself.

The score begins with "Sands of Time" and "Rhymes Have I," neither very well done, and moves along to "Baubles, Bangles and Beads," Night of My Nights" and "This Is My Beloved." The first two fall to Moore, who throbs appreciatively. Though Kitt's new number, "In the Beginning, Woman" sounded amusing, all her words didn't come through Saturday night. Kitt's cold style, however, fit the sophisticated character of the widow Lalume well. The arrangements remain more or less Borodin plus drum beats.

Price, as the groom, is superb in "Stranger" and "Night of My Nights," the latter taking the male chorus up one side of the house and down the other. (A Timbuktu custom seems to have been to deck the groom in white, or is that strictly Holder's imagination?) At all events, Price, who got on the map singing "Feeling Good" when "Roar of the Greasepaint" opened at the National, has become as fine a singer as he then promised. The dancing, more Holder than Mali, is a showbiz mix of Vegas, B'way and Club Mediterranee.

Now that triple-threat Holder has his costumes and dances rolling, his attention should go to direction and a reliable eggtimer.