Right. Something else to consider is that Pastrano was the same size as Bert Whitehurst, but an infinitely superior boxer, one who demonstrated his excellent legs and all-time jab over the 15 round distance against a definitive master technician. Pastrano certainly wouldn't have used the same suicidal approach Patterson submitted to Liston with. The worst thing Sonny could have done would be to intimidate somebody whose intrinsic nature was predicated on the stick and move. Liston might have gotten dizzy chasing him. Sonny also did not react well to the sight of his own blood, and Willie did register a few stoppage wins on cuts. Sonny would need to unleash his vaunted body attack very aggressively to take away Pastrano's legs.
I'd have to vote for either Chuvalo, Hagler, or La Motta. All three were inhuman in the punishment they stood up to at times and the wars they were involved in. (Especially when you think about Frazier basically caving in Chuvalo's cheekbone with his left hook and Chuvalo fighting with it and after it like it was nothing... apparently to this day his face is held in place by surgery).