Ali will always win against Foreman cause Foreman was slow as a snail. But 90's Foreman was better than 70's Foreman.
Big George just couldn't handle the speed of even that Ali. Ali would have made more use of his (underrated) left hook. In fact, I daresay Ali probably would have stayed on his feet more against Comeback George. who would have been so slow as to make MA show shades of himself as 60s champion. George was just too stubborn to get knocked down at that age, though, and far smarter/resistant to psyching. Ali would get a stunning UD, probably messing with George and rubbing his head toward the end of the fight.
He was better in certain areas for sure. He was more technically skilled, had some semblance of defense and indulged in the underrated art of timing.