If Evander Holyfield were champ in the 1920's, he wouldn't be required to defend against black contenders, therefore its a non issue. Then again, he wouldn't be champ for the same reason.
This is one that could go either way. Wills liked to control his oponents in the clinches and Holyfield would quite likley be able to match him at that game. Neither man is likley to score a knockout because Holyfield is too durable but not powerfull enough for Wills. It would probably turn on who was able to: A. Control the clinches. B. Outbox the other guy.
I dont think this is a likley scenario. Wills chin was prety solid. If Hollyfield was to win a decision or TKO would be more likley.
Langford was 31 the first time when the green Wills beat him. Sam was probably blind because Wills beat him 17 times