What incredible victory could your favorite(s) achieve, but at too high a cost?

The greatest fighters in the history of boxing have amazed us with taking on bigger, or much more talented/physically advantaged opponents and beating them. One wonders what would happen if they were pushed just that much farther to overcome an unreasonably difficult-and dangerous- match-up against an opponent with a significant advantage.

What fighters in history would be capable of even further weight jumps and stylistically PUNISHING bouts that would prove almost inhuman, but at way too high a price concerning their brain, career, functionality, and overall health?

No doubt some seemingly impossible human feats have already been achieved in the greatest sport in the world (Duran comes to mind) but some fighters are indeed willing to die in that ring, and I wonder what some exceptional individuals would accomplish under the real threat of doing so.

What comes to mind are things like Pacquiao against someone like Martinez at 154, old JMM vs someone like Maidana or Berto, Roy Jones vs any especially ranked Heavyweight...perhaps not the most thrilling examples, but they are some potential fights that get frequently talked about that make me wonder- if the danger was not a factor in taking the fight, could the heart, durability, and ability of such fighters allow them to get a win despite the likely permanent damage they'd receive?