To, me this seems like a match made in heaven. Lennox Lewis who fought in the 1990s was a great technical boxer with a damaging jab and damaging hooks. He was also a giant, standing at 6'5" Jack Johnson was about as tough as a fighter can get, spitting in the faces of white men in a time when the KKK would have hanged him over the nearest tree for simply being an uppity negro. Johnson was also a very technical fighter, who liked to punish his opponents, carrying them so that they would be out right exausted before the knockout. One of the most tiring things about him is the perfected clinch. You had to be stronger than an ox to get out of one of Jack Johnson's clinches. Often times, fighters fought Johnson with a couple of their teeth embedded into his gloves. Tell me what you think would happen in a 12 round fight, and a 15 round fight. Lewis SD12 Johnson Johnson TKO13 Lewis
Jack Johnson was not a KO machine. It would be hard not to imagine Lewis would stop him at some point, probably in the later rounds.
You could spot Johnson the plaster of Parris /doctored gloves, and give Lewis 16 ounce pillow stuffed gloves, and I'd still pick Lewis.
I mean come on...Jack was great for his time but he fought in an era where the sport was still in its infancy, with little competition, and often against smaller guys. He won his title from a 5'7'' 168 pound Tommy Burns...and that's one of the best victories on his resume...how much credit would people give Wlad if he beat GGG? You can show respect to past greats without putting them in absurd mismatches like these.
Johnson was the far greater technical fighter. Hard to pick a winner but I could see Johnson picking off Lewis punches at distance and scoring in close.