Pac got stopped about 10 years when he weighed as much as my cock, he was a wild, free swinging one handed fighter. Fights like that have no bearing on today. And 36 people alone on this thread said Pac would stop Hatton, it was always going to end in a KO for somebody.
Mayweather isn't a puncher and he fights off the back foot, the danger here isn't Pacquiao getting KO'd, the danger would be Mayweather outmanoeuvring Pacman and outboxing him.
Mayweather hasn't fought anybody as good as Pacquiao, just like Pacquiao has never fought anybody as good as Mayweather. Pac's kryptonite is a counter puncher, Mayweather's kryptonite is a fast, accurate, puncher with a great workrate and endless stamina.
Mayweather will do everything he can to avoid this fight, he's a cherry picker. Pacquiao will really have to force this fight and I hope it happens. The fight would be at a catchweight and I doubt it there would be more than 5 pounds between them come fight night, which would mean nothing.