I believe a Liston-Chuvalo title bout was all but set had Sonny won the rematch against Ali in 1965. I've always wondered this: Granted, Liston was definitely past prime by 1968 and Patterson a tad over the hill (tho he fought like the old Floyd against Ellis in September) but how about if Sonny and Floyd had locked horns in early-mid 68 for the 3rd time? Most agree that Patterson was tougher and gutsier post-Liston. A win over Liston may well have exorcised Floyd's "Liston-demons" AND elevated his reputation a bit more in the public eye. Would the older, grittier Patterson been able to best Sonny at this point in their career(s)?
If Leotis Martin can knock out Liston, then Jerry Quarry in the late sixties might too. Quarry would have to box early, avoid being cut, then open up with the heavy stuff after round 7. He might TKO Liston in 10 rounds.