Jack Johnson -vs- Joe Frazier…

Just fine? He was durable enough - it wasn’t as big a punch as it says on the tin either, Ali demonstrated this for us kindly about a thousand times lol.

 

I gree. Joe too hot, tho Jack would have Joe's head flying back with his uppercut s.

 

If they were timemachined into 1940, 15 rounds, ring-size and referee non-extreme, and my life depended on it, I'd go with Frazier, nervously.
If Joe came along in Jack's day, or vice-versa, it would be harder to pick; maybe I'd favor each a little in the rule sets of their own era.
I could see this fight as either guy starts off bad and gets more and more handled; conversely, I also could see Johnson getting a shock early but gradually reining in Frazier; or Frazier loosing early rounds but gradually grinding down Johnson.
Sort of like climbing an alpine peak, dropping an orange, and not knowing whether it's going to end up rolling into Germany, Italy or France.

 

Actually Johnson loved fighting swarmers. His skill set was designed to shut them down. He would do so vs Frazier by staying inside and controlling Joe physically catching inside blow at the elbow and countering with uppercuts. A dominant decision win for Johnson.

 

If wrestling and punching in the clinches is allowed then Johnson would do a number on Frazier.

 

Johnson wins by knockout. too versatile, too many guns for the limited Frazier