Based on styles, I lean toward Frazier. Norton was a forward-moving plodder, who didn't fight on the back foot and didn't clinch. Norton didn't have the lower body strength to push Frazier back. I think Frazier would push Norton back and get in his chest.
Frazier liked Norton, Ken was his sparring partner but he was all wrong for Norton...Frazier backed you up and he did it with hooks to the body and head...once hurt Kenny is done and I expect it to be within the first 3 round for Joe to turn up the smoke...Frazier by KO 2-5 rounds
I fully agree that this would come about in a prime for prime scenario. Even in an actual meeting between them before,and during 1975. In '76 I'd give Ken a damn good shot.
If you had said prime for prime, then for me the incessant pressure of late 60's/early 70's Frazier wears Norton down. But post fight of the century Frazier was slightly chunkier and more battle-worn, I think Norton would find that version a lot easier to pick off and perhaps even wear down himself.
Watching the Foreman- Frazier 2 fight, Frazier moved well for being over 224. Joe wouldn't be backing away from Norton and judging by the Uniondale fight, Joe would have got his shots in on Norton. Moving forward instead of backward, Joe would have stopped Norton in '76.
Good point raised there, I find it hard to think who takes the lead. For me a lot of who wins this mythical fight is based on who takes the lead.