Johnson never had to deal with a jab like Foreman`s or his power, he would have stopped Jack eventually, clinching would have been a problem for Jack because Foreman was so much bigger.
Jack had the skills to beat a lot of styles and sizes. If he can avoid that booming jab and right cross or at least nullify it, take George in to the later rounds, then Johnson has a chance
I'll take Old Foreman. Stylistically JJ is a midget trying to hit and hold a fighter that's not only much taller than him, but also strong as a house and 50lb heavier. He'd be playing right into Foreman's hands.
Johnson by decision. Too clever defensively, too fast, and George was hittable. Johnson would not tire either.
Johnson obviously won't manhandle Foreman. I don't think he has the range, given his reach and footwork, to stay away from Foreman's jab for long. And his low hands are going to cost him. Foreman KO8
Keep in mind that Johnson was bigger than many of his opponents back then. They called him the Galveston Giant, despite Johnson only being 6 foot and a half. Not to mention that Jack Johnson was knocked out by 5'11 Joe Choynski in 3 rounds! He would not be able to man handle a 6'3 1/2 Big George around. It would be the opposite. For those reasons I think George knocks Johnson out. Period