With last season's Purlie at the Goodman, last Fall's Raisin at the Court and this production of The Wiz, Chicagoans have been given the chance to visit or revisit three of the hit African-American-themed musicals of the 1970s (Ain't Misbehavin',Ain't Supposed to Die a Natural Death and Bubbling Brown Sugar are also in this group.) The Wiz, though, can be called the king of this class, boasting a four-year Broadway run from 1975 to 1979 and a 1978 feature film translation starring Diana Ross, Michael Jackson and Richard Pryor. It's a good choice for White Horse, a five-year-old company of not-all-that-recent college grads who focus on less-performed musicals that can loosely described as youth-oriented. It's a generous choice as well. Though company members Craig Joseph, Ryan Brewster and Baron Clay provided the stage direction, musical direction and choreography, White Horse turned over the stage to African-American guest artists to perform this show, one of only two productions in the company's season.