Ten rounds? I’d have to say Conn. Dempsey hadn’t fought in years & may have been ill on fight day. Conn’s only lacking in a serious one-shot punch insofar as being a major force at Heavyweight.
Conn was a heckuva fighter and a brave man. I doubt he was as strong as Tunney, although there's no way to prove it. He simply doesn't look as strong on film. But he's fast and in his prime he threw lots of punches with both hands and had good footwork. His punches were stiff enough to rock Louis momentarily. Could prime Conn defeat a Dempsey who has begun to slip? Certainly not impossible.
I could see Billy Conn ahead on points and getting knocked out late. Even that version of Jack Dempsey was still dangerous.
