Orson Welles' The Magnificent Ambersons ..... I've going to give it a go pretty soon with storyboard illustrations, surviving stills, the Criterion laserdisc presentation of Welles' radio play, and this book.
Supposedly the studio sent the full version to Welles in Brazi to editl, then they promptly chopped it up for release (142 to 88 minutes,) and burned the rest. Next time I'm in Brazil I'll have to check the pawn shops.