I actually wrote a short story about the Frazier vs. Marciano one, though I was assuming 12 round competitions; more in line with today's standards.
I'm on edge about the decision to give Foreman a KO over Mike, but it could go either way.
Holyfield would be the sleeper in an event like this. That's what happened when I ran the NCAA 64 style bracket a looooong time ago; a lot of people kept on voting for him to steal wins, and it was possible given his skill, strength, and heart.
Coincidentally, the finals (based on votes) ended up:
1. Ali vs. 3. Tyson
1. Holmes vs. Louis
Ali vs. Holmes