Originally posted by Don Sonny Corleone:
Call me crazy, but I saw a commercail for the Elf DVD and it showed a clip from an extra, and (going by looks) Will Ferrel looks a hell of a lot like a young Sonny. Granted, Ive never seen do anything that isnt aimed at the 12-17 year old audence, so who knows if he can really act, but just a suggestion.
EDIT-fix typos.
Holy Hell, I'm typeing like Mike Sulivan 
Will Ferrell is in his mid-30s and is considerably taller than Caan, I believe. You can't have Sonny being 35 years old and 6-4.
