Ali's speed and mobility would be the key here ,in and out before Lewis could get set. I do think Lewis is stylistically a very tough match up for just about anyone , but Ali is not ' anyone'.
Ali is one of the most mentally tough fighters in the history of the heavyweight divison, right up there with Evander Holyfield. He could handle it.
Lewis wasn't that much bigger than Ali. I mean, Holyfield and Mercer did pretty well against Lewis's size and they were no bigger than Ali, and probably less rangy. Size isn't everything. Lewis was awfully big and strong at 6'5 and carried anything up to 250 pounds on his frame pretty well, but most good heavyweights are prepared to fight men like that and often even the smaller ones have success against men who are a lot bigger. Lewis used his size well, but big guys like Grant, Akinwande and Klitschko were beaten up quicker than some of the smaller ones who proved difficult.
Lewis was a whole lot smarter, bigger and more capable than Ali's challengers in both of his reigns. He could do anything that Norton could do in terms of making things difficult for Ali, only better. Name a challenger that Ali fought that was as capable as Lewis, and don't say Foreman...Lewis trumps him, or Norton, again, there's no comparison...in terms of size, don't even bring up Ernie Terrell.
This is how see it as well. There are most certainly a large number of fighters who I don't think would match up well with a prime Lennox Lewis. Ali however, was of reasonable size at 6'3", 215 Lbs and had speed along with durabilty to match Lewis's physical attributes. Who would win? Subject to debate I suppose.
All Ali has to do is make Lennox use those size 17's to do everything. And Ali was very comfortable fighting a retreat type fight and had the lateral movement to circle away from the Lewis right hand and Lennox really doesn't throw too many left hooks to try keeping him at 12:00 so he can plant his feet to punch Ali. A decision bout all the way & it was never easy beating Ali on the scorecards.
The real question should be whether or not lewis could handle Ali's speed and unorthodox style. Lewis, though 2 inches taller and over 25 pounds heavier, would find Ali very difficult opponent because of the speed factor as well as the elusiveness. I doubt that he would be able to keep up, so this is a case where speed neutralizes size.
Come on. We all know that can go the other way as well. When did Lewis ever fight anyone like a Muhammad Ali ? I don't think Lewis's size really matters in this fight. He's got a longer reach than Ali's, which could make it interesting. Lewis likes to grab smaller guys who need to force their way on the inside. Then he leans on them, a la the Tyson fight, and saps their strength. But Ali is moving in and out all of the time, he won't fight like those others have to. He's going to go in, get off with the speed, and then get out. Lewis doesn't have the speed to answer that challenge. Also, he's just too tentative a fighter to really enforce his will on Ali. If he tries, we know how effective Foreman, one of the best fighters in terms of overwhelming his opponent, was.