Fan Casting Immortal The Godfather

Imagine a world where actors and actresses never died and could reset or jump forward to whatever age they wanted, whenever they wanted. In this hypothetical world, who would be the cast of the three The Godfather films? Any actors, dead or living, old or young, are allowed as long as you believe that at some point in their lifetime, they could have been, or will be, a good choice for a particular role in The Godfather. Actors who have been in a Godfather movie are not allowed for the roles they already play, but they can be nominated for roles they could have played at a different age.