That seems like a strange thing seeing how he was 32 and had the miles of FOTC and the two tough fights against Norton behind him, but I agree that that was arguably the fight he looked best in post exile. There was a lot of holding of course, but he moved well and rattled off fast sharp combos.
I also feel like Evander Holyfield looked like his best ever in the Bowe 2 and Tyson 1 fights despite the beatings he took before, simply due to the style adjustment, pacing himself better and being wiser. Maybe physically 5% worse but mentally, technically 20% better.
Bowe 2 might have been the very best Holy, yes. He started to slide pretty rapidly from there due to age, wear and tear and health problems, but I'd agree that the Tyson fights probably saw the best Holy after 1993. So, yeah, that's comparable to Ali quite possibly looking his best post exile for the Norton and Frazier rematches.
Norton 2 was his best performance in the 70s IMO, Ali showed great movement throughout the whole fight and looked very sharp. For me that's the only fight where he looked like the 60s version of himself.
Post FOTC, he looked close to his best from 72-74. Obviously the first Norton fight was the exception
Frazier took a beating and was hospitalized after the FOTC but this is the first time I read he was near death.
You're right about the punishment Ali was landing on Frazier, but Joe kept coming and he started dishing out pain by the truck load and Ali began to wilt under that assault. Who could have beaten Ali that night besides Joe? I wouldn't bet on anyone else to do it.