Adjustments were made for sure. But when I think of examples with Steward I don't see anything in Lewis' performances that erase the chances of joe Frazier of the first Ali fight. Shorter opponents like Butler, Fortune, Mercer and Tua were with Steward. I didn't see Lewis handle them in the style of George Foreman.
Frazier had a better chin than Lewis no question. At the same time Joe`s was much easier to find with clean shots. Frazier had physical limitations so he had to go into the blazing guns of his opponents. Lennox could hide his chin much better and when he was hurt he could blunt the follow up attack. This is not a good style match for Joe Frazier. He`s got an opponent who is smart, bigger, stronger and has elite power.
I think Ali hit Joe a lot of times. I'm not so sure he got hit much more than anyone else in his earlier fights though. Nodody was hitting him as much as Ali. At least not before their fight. Fraziers momentum forced the opposition to respond to him if they wanted to or not. Joes offence was his defence. his slip rate was really good, he could get timed, there was a sequence to it but if you hit him a punch was already on it's way. He made everyone think about what he was going to do to them rather than what they wanted to do. That's a great asset. Lewis would be hitting down. He was not so instantly effective as you might think against fighters like Justin Fortune and Butler as he would need to be versus The Frazier Ali fought. I don't think prime Frazier was easier to hit than Justin Fortune. The tempo of Frazier would panic Lewis. It could destroy the composure Lewis needed. He won't react well to that intensity
Frazier was nearly always hitting up so that's not anything new. Lewis' chin is only 1.5 inches higher than Foreman's was. 2 inches higher than Ali's. An inch higher than Joe Bugner's. 2 inches higher than Bob Foster's. 2 inches higher than Mathis's. Frazier had no problem reaching the guys who were 6'3 and 6'4. Lewis's 6'5 height wouldn't be a challenge.
I not sure Lennox was the full 6'5 he only seemed around 2 inches taller than mason who was billed at under 6'2 when they fought. Diddnt look 3 half inches taller than 6'1.5 Evander either imo I think Lewis was more 6'4 than 6'5. So as you say Frazier wouldn't have too much trouble finding his chin as he fought several people of similar height and landed plenty!