Sonny Liston vs Leon Spinks, both prime, 15 rounds. Would The Big Ugly Bear of 1959 cower when he sees the dangerous Leon Spinks from 1978, with a large physique?
I do see Liston lasting longer than Foreman utilizing his superior boxing skills to stay away from Spinks as Liston was very smart in the ring, he'd know it's in his best interests to avoid a slug fest with Leon. It serves him well, and he even manages to win a round on one judges scorecard (though the other 2 still scored it for Leon) which ends on a slight hint of hope for Liston. Unfortunately, Liston learns you can't run forever. Spinks catches up and finishes what Cleveland Williams started. Spinks TKO9.
Oh I forgot about that. That's going to be the biggest advantage of Leon's. Liston's infamous stare can't hold a candle to Leon's grin. I expect Liston to cower in his boots when he sees Spinks is not only completely unafraid of that legendary stare but gives him the toothless grin in return.
I believe Spinks might be in the lead vs. Liston, since he didn't always go for the knockout in round 1. But I am confident that Liston would win by TKO in 3. I think @Richard M Murrieta, that u should make Spinks posts with less obvious outcomes. Leon would probably get TKO'd by Williams too, but hammer out a decision vs. Terrell.
Leon gives Liston a tough physical fight for a few rounds but ultimately Liston's much greater power folds Leon in the mid rounds.