On a lighter note, things would have been very different had Lawrence Olivier (Coppola’s original choice) played Don Vito Corleone and John Cassavetes has played Michael as originally intended.
Olivier would’ve been a curious choice, although he didn’t have the raw physicality and menacing presence of Brando (and age was a factor, he could not have played Don Vito in his 40s). John Cassavetes was also too old to play Michael (he was too old for “The Dirty Dozen”, too, for that matter, as were most of the other actors, especially Telly Savalas). He could not have convincingly played a “little brother” to James Caan and John Cazale. Pacino was able to play the age range from a baby-faced college student to near middle-aged by GF2.