IMO If they had a series at CW, Holyfield wins 2-0 and there is no 3rd fight. If they had a series at HW, Holyfield wins 2-1 (if it's the Holyfield up thru Bowe 2), any version after that Usyk goes through (with some difficulty but still pulls it out)
Moorer was fighting at 175 lbs at 23, Usyk was fighting at 200 lbs in the amateurs from 21 years old. Usyk was a middleweight as a teenager, Moorer was a light middleweight at the same age. Moorer was less disciplined than Usyk and came in fatter in many heavyweights fights. "Much bigger" may be too strong but Usyk is billed as an inch taller and half a stone heavier when comparing their best performances.
Holyfield from Bowe 1 would batter Usyk. Usyk still hasn’t fought a contender at HW so the verdict is still out… Chisora gave him all he could handle from what I recall