Larry Holmes, Tony Tucker, Pinklon Thomas, Michael Spinks, and Andrew Golota are all better wins than Ken Norton, IMO. With Ken Norton, he had the kind of style that gave slick fighters like Ali and Holmes trouble, but he could not hold up to aggressive power punchers early, as evidenced by what Foreman, Shavers, and Cooney did to him. Mike Tyson fought cans AND the best HW's of his era, generally winning those fights emphatically. He wasn't just a can crusher, that's a myth that's been perpetuated about the guy for far too long. His power was very close to the greatest power punchers of all-time, Foreman included.
Also, I'm sure it was just a turn of phrase, but you do realize that while Foreman was busy KO'ing Frazier, Mike was actually busy being about 8 years old, right?