I'm with SC! I read the novel many times before the movie was made (or the casting announced). Wasn't familiar with anyone in the cast except Brando, Conte and Hayden, all of whom seemed logical choices for their roles. A major part of the greatness of the GF Saga was Coppola's brilliant casting--and brilliant directing in bringing out the best in the cast he chose. I've never thought of any other actors in any of the parts ever since.