If Floyd fought in the 80's, he never would have jumped past 130. He had Arguello waiting
at 135. Aaron Pryor at 140. Forget about welterweight. Leonard, Hearns, Duran and later
in the 80's there was Donald Curry. Floyd is the best match maker of all time but would be
lucky to be one of the 5 best welterweights of the 1980's.
Mayweather is certainly the best illusionist and match-maker in boxing, knew when to fight guys, stacking everything in his favor, including drug-testing... But he'll run through those guys, mostly easy work, too fast, too athletic, better IQ, better strategist, with enough power to stop most of them... Maybe Hearns will give him problems early with his size and lenght, but Mayweather would win in the end...
Regarding Hearns-Duran, that was an horrible size-mismatch, in today's era it would be seen as a cherry-pick on a much smaller, older man, while it's overall rated as an all-time's great win, lol...