I cannot imagine the best version of Jack Dempsey being held off by the best version of James J. Corbett for very many rounds. I would say Jack Dempsey stops James J. Corbett inside of 6 rounds, and likely in a brutal way. Release the Corbett and the hunt is on!
I always say a boxer beats a puncher more easily than viceversa, reason which, while being a neutral fan, i always favored Mayweather over Pacquiao. Corbett could definitely beat Dempsey. But Dempsey had that punching power of his...