Zaire sounds about right, but I wouldn't place large bet till 1975 or later. Put prime Liston in Manila and we see a very ugly sight.
Here is what Emanuel Steward had to say on this subject and that of Liston. Whilst i doubt peak for peak Sonny would have won it gives a snapshot of just how highly Steward thinks of Liston. We'd had a couple of great posters in here over the years taking the exact same stance. Q: If Sonny Liston had gotten his shot earlier against Floyd Patterson and if he didn’t have Ali coming up, how good could Sonny Liston have been? A: Sonny Liston, I watched Sonny Liston when I was a teenager do something that I’ve never seen any heavyweight do—walk through the whole division almost from being the number ten guy all the way up to the champion because he was that devastating like around ’57, and ’58, and ’59. I mean he had unbelievable brutal punching power. He was mean, punched with both hands, and I think that the time that he finally got to the title, I think his best years had gone and right after he won the title he began to live the life of a middle aged wealthy man. He lost the real focus that he had earlier. ’57, ’58, and ’59 he was one of the most vicious machines probably ever in boxing, but after he won the title, from my reports and from what I gather, he started drinking a lot and he was golfing and he just lost that total edge. He was living the life of a comfortable man and then here comes exactly what the computer prints out—the thing in the world for him. A fast, young fighter, good movement, a solid amateur background, and who had been fighting on a regular basis, so therefore when the match-up came it was just perfect timing for one, terrible timing for another guy who had slipped past his prime—but if they had fought, in like say ’58 or ’59, a prime Sonny Liston and a prime I would still say Cassius Clay or whatever—I don’t know. I don’t know. Sonny at that stage was just such a really powerful wrecking machine and I remember the fights he had with Cleveland Williams—oh my God. I don’t know, Sonny might have won if they would have fought at that time.
In a sense, Sonny's legacy actually benefits by having more time to show his hunger as a contender. Moving forward the timeline of when he gets his belt probably just moves forward when he starts resting on his laurels and gets upset. I can't knock him for taking it easy once he got the belt. It's hard to come from nothing and not want to celebrate and relax a bit once you become champ. Happens to a lot of 'em.