Personally, I don't see him beating Ruddock or Wilder (up until the 2nd Fury fight). Ruddock was tough, awkard & durable. He would land "The Smash" at some point. Wilder pre-Fury 2, was awkard, energetic, herky-jerky & had a knack for always landing that big right hand. His right hand would crash into Norton at some point.
Wilder would have been pulverized, he was mostly too slow on the draw. Norton would have been all over him. Norton in 8, 9 at the latest.
There is no big puncher that Norton would beat. He froze like a deer in the headlights every time he fought one. He did well against boxer/counterpuncher types but anyone with a good punch could crack Chinny Kenny.
I think Norton beats Mike Weaver. Mike was powerful but not aggressive enough to take out Ken early. A warmed up Norton wouldn't be as easy to stop.
I don't see what the assumption with Ken being able to last better if the fight goes into the later rounds comes from. He got knocked out early by Foreman, Shavers, and Cooney early, not because he was some insanely slow starter- But because he didn't have the chin to last any more than 1 or 2 rounds against each of these guys! His chin does not magically get better as the rounds go on, and he has no record of doing good against big punchers after surviving close calls... He simply gets plastered.
Slow your roll. It's a thing. Fighters get caught cold in the 1st round might be hurt. That same shot later on they take it without blinking. Not every so called puncher is taking out Norton early. Weaver for example as I already mentioned wasn't as aggressive as a Foreman etc. Oh and 2 out of the 3 guys that stopped Ken early Norton was either totally shot or close to It.
It's a thing, but it's sure as hell not a thing with Norton. I don't think that most punchers will take him out early, I'm saying that Ken's chin will not increase in durability as rounds go on. Even if he doesn't get stopped early, he is at risk of it during every single round of the fight when up against someone like Weaver.
The best big puncher I’d pick him against would probably be Mercer or if you don’t consider him as so because maybe he’s not a devastating puncher, I’d probably say someone who doesn’t have a great punch selection when throwing combinations like a Rahman.