August Wilson's 1996 elegy about dreams deferred is an epic drama, but it's also long and verbose, and anyone who has seen it before could be forgiven for approaching yet another production with foreboding. So the shock here was the amazing pace of last January's St. Louis Black Repertory Company staging. Six of the seven actors had appeared in other Wilson plays. From experience, they knew the importance of propelling the action forward. Act 1, in particular, was performed with seamless splendor. But the entire evening was a reminder of how enthralling live theater can be. The Black Rep production of Seven Guitars did what the best theater always does: It left memories that continue to reverberate, and even haunt, the mind.