One of the top light heavyweights of his era, he was a champion at that weight. A slick stylist in short. He fought on as champ (i'm sure) when past his best. Boxing folklore now reads that his good friend Joe Louis accepted his challenge at the heavyweight title on one condition; if Louis beats him he retires. Louis didn't want his good friend to carry on when past his best. Louis stopped him in the first stanza and that was that. I couldn't see him outboxing Lennox, i think he'd get stopped personally.
John Henry was a fine Light heavy,and he did stop Elmer Ray ,but Ray was over 40lbs lighter than Lennox. Size isnt everything, but, when its allied with skill and power it takes a bit of surmounting.
I think that Lennox, who has never faced a good light heavyweight like John Henry, is caused all sorts of problems. He is a totally different proposition than anyone Lennox has fought. Lennox made his name on facing tall physically imposing fighters who hit like trucks, which plays into his hands. It has been proven time after time that World class light heavys (see Spinks, Tunney, Conn, Fitzsimmons, Moorer etc) can compete at heavy and do not simply fold with the first punch that is landed. John Henry makes a serious fight of this, causes major problems with his speed advantage, and definitely gets Lewis attention with his power (even if he doesnt hit as hard as most of Lennox' opponents). Saying all this, Lennox is not just an average run of the mill big guy. He will eventually hit John Henry Lewis as hard as he has ever been hit before. And it will wear him down. I think Lennox knocks him out around the 6th or 7th round in a close fight, although Lennox is probably even or ahead on points.
While I generally agree with your assessment of this fight, I wouldn't say Lewis's name is based on these kinds of wins. Yes, he won fights as against Golota, Grant, Klitschko, Biggs etc., but two of his most significant wins were against Holyfield in March 1999 (we all know he won and won in dominant fashion) and against Tua. I don't like Lewis's resume has a blind spot with regard to this kind of opponent. I think how well JHL does depends largely on how well he can make his shorter stature work for him. Tua may have not done well against Lewis, but he did manage to avoid Lennox's heavy artillery for most of the fight by keeping low. What success Tyson had was due to dropping below Lewis's punches and bulling in; Mercer managed to make his shorter height work for him etc. I tend to think JHL was the kind of skilled practitioner who could do this and therefore would do very well. Provided both men are on form, I think Lewis would either catch him on the middle rounds as you suggest or win an awkward decision, with JHL having winning many battles but losing the war in a skilled, tactical fight.
Henry Lewis would likely be the quickest fighter Lennox ever faced and could do well in the earlier rounds, however I feel Lennox would take over and stop him in the sixth or seventh.
John Henry wins the first three rounds, before Lennox asserts himself, and wins it in the seventh by Kayo.
Under very special circumstances: Spinks against an old unmotivated Holmes when he himself weighed 200, Tunney against an old Dempsey who was most certainly not a modern heavy in stature, Conn who did well but got KO'd against a sub-200 pound Louis, Fitz against a 190 lb Corbett, and Moorer who was a fit and legit 214 pound heavy when he got the title, not a light heavy. The match-up idiosyncrasies that allowed the above to occur are nowhere to be found when pitting a prime Lewis vs. JHL. KO2.
It's hard to say how it would go. I'd expect Lennox to win certainly, because he's massive and he's pretty quick for his size, and he's a decent boxer. John Henry knocked out some pretty big guys but no one as big and good as Lennox. Still, JHL might be able to last a few rounds, or even the distance. I don't really know his style. I know he was great though, and I know he was only stopped by a peak Joe Louis, and only then when he was going blind and ready to retire.