There were many Cuban amateur greats and they beat alot of young fighters before they became stars, but the Cubans were 20-30 something yr old guys in their primes, while the guys getting ko'd were still very green. Stevenson and Savon were some of my favorites, but you could say they were never tested because they never fought in the pros, but they were very tall fighters, extremely skilled, and athletic and the prototypes of the ones we know today as the Klitschko's. It's like comparing the minor leagues to the major leagues. I'd go with the more proven Ali. He paid his dues to be the best HW ever.
Ali would batter the **** out of him. It would be simply unfair to match an amateur, no matter how good against a top professional, even before amateur boxing was utterly ruined.
No real proof just opinion based on professional COMP Vs. Muhammad Ali by 15 rds of beatdown & some **** talking to boot.