Take all the former HW champs, put them in a 1/2 acre cage with gloves on. No kicking, no wrestling, no low blows, no elbows, no hitting from behind, no hitting a man who is down and no other rules. Last man standing would win. Who would you bet on? I think I would bet on Marciano. Liston or Dempsey might also be good bets.
Lennox, standing in the corner and using his reach to flatten anyone who gets close. Or the K bros if they tag team up.