Of course Ruddock makes a good contender in the 70s and he would be dangerous for Joe Frazier, even though Frazier is the greater fighter. Quarry would be a bit small for the 90s, but not much smaller than early 90s Holyfield. He would not beat Lewis, Holyfield, Tyson or Bowe.
Yes I can see him being dangerous for Frazier, he hit hard enough. Joe gets a decision over him or a late stoppage, especially if it s 15 rounds. He'd be deadly dangerous against Norton, he maybe stops Lyle or Shavers. Quarry would maybe get wins over Mercer possibly, Bert cooper, maybe Moorer. Guys like Tyson, Lewis etc are definitely a no no for him.