On their very best night who wins the all time heavyweight prizefighter competition?

[Dark Lord Al]

over the short distance wouldnt George Foreman have a chance , the free swinging destroyer who beheaded joe frazier ?

Possible, but I think the Ali and Foreman were pretty level in terms of their closeness to prime when they fought in 1974 and look what happened

You should check out his fight vs Gregorio Peralta, he was a good boxer a veteran. And he laid down the blue print on how to beat George Foreman, who was tired and frustrated at the end of the fight.

Yes the problem with that is Foreman was not in his prime for that fight , and one would have to presume he learned from the fight.
This is why its so hard to compare era's.