Prime Sonny Liston hands down on this one, 1991 George Foreman was ponderous, he could hit but was a lot slower than the prime Foreman of 1973. He did learn to box better, but very slow, also older and heavier. Sonny could take a punch, in 1954, he had his jaw broken by one Marty Marshall, he fought on to lose on points. In 1959, he had his nose broken by Cleveland Big Cat Williams, only to knock out the Big Cat, early. He could also go the distance as he did against Eddie Machen, in 1960, in winning a unanimous decision. The Bear had a pole like left jab, good head movement, and a crushing right hand that was seen in his knockout of Albert Westphal, in 1961. Sonny used to say that the prison guards hit him harder over the head with clubs than his opponents. Sonny keeps slow Foreman at bay with his left jab, familiar with George's style, as they once sparred together, Foreman unable to penetrate Liston's defense gets desperate, tries to fire a clubbing overhand right, Liston moves his head and lands a counter right hand, spilling George onto the canvas in round 4. Foreman arises, clinches, the fight then continues to round 9. George's right eye is swollen shut, Sonny rains combination after combination, forcing the referee to halt the fight in favor of Sonny.
I think more than anything else, it is possible, because this version of Foreman had too much extra weight to carry into the ring against a fit Sonny Liston. Just plain exhaustion and taking punches from the Bear, would be the deciding factor as well as the familiarity in sparring, years before. Willie Reddish would have Liston in great shape, because this version of Foreman would not be a walk in the park by any means. In 1977, Jimmy Young put prime George Foreman on the deck in round 12 of their fight, Jimmy did not even have the punch that Liston possessed, but from a variety of combinations and exhaustion, Foreman arose in that fight but lost on points anyway.
I see prime Sonny winning a unanimous decision. Both might have knocked down the other during the fight, but at that stage in their respective careers I highly doubt it.
I don't see it that way, Rules. Sonny's punches are straighter and George had little defence then o I could actually see Sonny busting George up. The patented Foreman shove off tactic won't work as Sonny is too upright so George would have to use his jab to establish distance and he won't win a battle of jabs with Sonny. Holmes and Ali could beat Sonny in a jabbing match with their speed; nobody could match thudding jabs with Liston though. Young George would win fights much more emphatically than old George but was less savvy defensively and didn't take as good a shot, had less stamina and was a bit more mentally fragile. Of the two Foremans, in this instance I actually think the older one does better vs Liston but it won't be enough. Liston is all wrong for either version of George imo but this may just be my dream hypothetical heavyweight fight.
I think it is a really bad fight for 1991 George Foreman. Its the exact kind of fight George avoided on his comeback. Prime Sonny Liston was a great fighter. Prime George Foreman was also a great fighter. But comeback George Foreman, whilst strong and brave was extremely limited at world level. A fight with Sonny Liston is an echelon higher than world level. This is an all time great fighter. Remember what Alex Stewart did to Foreman? And Alex Stewart was a poor mans Sonny Liston. A guy losing to Tommy Morrison is not beating Sonny Liston.