I think a lot of people are underrating Norton's chin sure he froze in some fights but guys like Shavers, Foreman and Cooney had massive power very few heavys have that kind of power. I think Norton would beat Gene via a competitive decision.
While Ken's style would create problems for Gene, Gene would be ready for it on fight night. Despite what some seem to think, Gene had some pop in his punches, enough to get Ken's attention at the very least. I'm going with Gene by a close decision.
Tunney, decision. Big advantage in footwork and he'd turn Kenny in there and just flurry to score the points. Tunney had boxing brains and he'd have to use them. And I think it'd be easier for Tunney to solve the crossarmed defense of Norton's then it'd be for Kenny to solve Tunney. It's going to be hard for Norton to land those wide looping hooks to the body on this guy. Good fight and good matchup.