1. John Ruiz
2. Gerry Coetzee
3. Marvin Hart
4. Primo Carnera
5. Leon Spinks
6. Frank Bruno
7. Sergei Liakovitch
8. Bruce Seldon
9. James J Braddock
10. Trevor Berbick

and let's not forget the great Nikolai Valuev.

And, yes, I know that some of these were heavyweight 'Title holders' and not world champs. But an illustrious list nevertheless.

I'm pretty sure they would all beat thse guys up:

Joe Louis
Jack Johnson
Muhammad Ali
Sonny Liston
George Foreman
Mike Tyson
Jack Dempsey
Sam Langford
Joe Frazier
Rocky Marciano