If I knew that both were motivated to fight...
Without a doubt, I would
heavily favor Roy Jones.
knowing that it's an exhibition, and knowing that there may or may not be financial incentives to manipulate the decision... = A 'Fun', small action bet on whoever you like.
Tyson is the bigger 'draw', here. A knockout by Tyson could lead to another payday... an exciting controversy could lead to a re-match and another payday...
It's a fun distraction of a story. I'm already surprised, and entertained. Rooting for good show, and that both of these retired stars have a safe event.