How would old heavyweights do in the division if they were adjusted for size ?

[Dempsey19]

I recently read some articles in which they were adjusting the size of older heavyweights to what they would be if they were born today, by comparing average height and weights, etc. and this is some examples of what they got.

John L Sullivan- 6'2" 225 pounds
Jack Johnson- 6'4" 240 pounds
Jack Dempsey- 6'3" 210 pounds
Joe Louis- 6'3" 225 pounds
Rocky Marciano- 5'11" 206.5 pounds
Muhammad Ali- 6'2.5" 228 pounds

If the old heavyweights were this size, how would they fare in the modern heavyweight division ?

[Heavyhands420]

Without size adjustment i still think they would do well. People like dempsey or tyson even though short for today would be stylistic nightmare for people like wilder. Theyd break him and joshua down with body shots and power punches to the dome. There were some big ass dudes still back then. I think the footage from then just makes em look slow. But one thing is for sure they were alot tougher. Anyone that was a champ then would most likely be champion today. Id have anyone on your list beating joshua right now. Other than wilders power nobody looks “special” in the heavyweight division right now. Id give all those champs a good shot currently

[Dempsey19]

People like dempsey or tyson even though short for today

Would Dempsey really be that short ? He's taller than Chisora and Takam and about the same height as Rahman, Stiverne, Ortiz, Purrity and Brewster.