Lewis: much too big and strong- not that Joe didn't KO big guys- but Lewis is also very athletic: not a big lumbering punching bag. Frazier would never get past Lewis' jab. imho.
I'd have to go with Lennox Lewis 8 to 9 times out of 10. (mostly by KO, but probably some decisions too) During his prime he was barely over 200lbs. Against a huge, talented and athletic giant like Lennox he wouldn't even look like a Cruiser Weight fighter!
Frazier's only hope in this one is to run into an unprepared and unmotivated Lennox. If Both guys are prime, and bring their A-game, Smokin' Joe gets smoked.
Why? A smaller puncher who uses a herky jerky bob and weave defense and high workrate, hooking offensive style would be trouble for Lewis's slower, though powerful jab. He'd be able to get in moreso than any other Lewis opponent, and that left hook would likely land at some point against a Lewis not at his very best. If so, I could see Lewis doing enough on the outside and coping defensively and in the clinch on the inside.
Replay of the Foreman fight but a few rounds later because Lennox would respect him. Anyone who picks Frazier in this ATG matchup has lost their mind and doesn't understand the fight game whatsoever.
A less than best Lewis, who knows? But I said...if both guys bring their A-game. Lewis' height would make for a bad angle on that hook. Frazier might burow his way in but if he did, I can just see the backward somersault he'd do from the mother of all uppercuts !
Unless Smokin' Joe gets a good shot in early on that suspect chin, I don't see him winning this fight.