Every great fighter has strengths and weaknesses. Dempsey's assailants, are increasingly unwilling to acknowledge his strengths! The mark of bias against a fighter, is to withhold credit, on the variables where they are generally considered beyond reproach!
His strengths are proven against good fighters but not the best of his era. How do we know his strengths will work against the best of his era if we didn't see it? And what is beyond approach with Dempsey?
In a bare-fisted bout Dempsey must be favoured. He was accustomed to throwing down with men much larger than himself after a long day's work. Louis, as brilliant as he was with the gloves on never had to endure this kind of hardship. Jack would probably thump his eyes shut.
With gloves in a modern 15 rounder I would pick Louis. Bare knuckle it's a different story. Dempsey by early ko. Both hit on par but Dempsey was quicker, rougher, and had better whiskers.
Louis is made to order for the fast striking, in and out brawler in Dempsey. Louis does better as the fight goes on, but my bet is an early KO for Jack, Louis is counted out in around 4 rounds. ( with gloves or without)
If I remember correctly wrestling was allowed under LPR rules. If this is correct then I would give the edge to Dempsey. He did a lot of wrestling in his training regimen and was pretty proficient at it according to the wrestlers that he trained with. Add to that his many barroom brawls and s****s in the mining camps where he worked as a youngster and you have a pretty dangerous bare knuckle fighter. Under modern rules I would favor Louis (Not by a wide margin mind you) but in a bare knuckler with suspect "tactics" allowed I would go with Dempsey.
Dempsey ducked Wills, no question there. And Greb deserved a title shot more than some of Dempsey's challangers. But I think it is a stretch to claim that he was the second best heavyweight of the era. I mean, based on what? He beat Dempsey's weaker challangers, but he did not face Jack's more dangerous opponents, Fulton, Willard and Firpo and he lost to his best challanger Tunney. He is the best fighter of the era, but what makes him the clear cut number two heavyweight? As for the question, who knows? I've never seen a fight with London prize ring rules so Im shooting in the dark here but if wrestling is allowed that should tip balance in Dempsey's favour.
A meaningless question also deserves an answer ... 1-Dempsey and Wills DID sign for a fight that was cancelled because the Michigan Promoter couldn't come up with the funds... 2- Were they to have fought Dempsey would have been a big favorite as the big slow guys were easy pickings for Jack. 3- Watching film of Harry Wills, he reminds me so much of an earlier edition of Ernie Terrell in his straight standup style... 4- When asked by reporters who would win between Jack Dempsey and Joe Louis at their bests, Jack Sharkey who fought an older Dempsey and a prime Joe Louis opined " well if you put them in a closed room and locked the door, Dempsey would be the man to walk out ". For what it's worth...