Don't think Maywhether was as agressive as Sugar Ray Leonard. Leonard forced his will on Hearns after trailing on points and rallied for the TKO victory. I don't Hearns was as strong at WW as he was at junior-middleweight. But he is still a much larger man and Maywhether would not have answers in this match-up. Hearns UD or possibly late stoppage in a 15rd fight.
Mayweather is the best welter NOW. Only one guy has a real chance with him, and that's Cotto. When you bring up guys from the past there are 3 welters against whom Mayweather would lose nearly every time; Robinson, Leonard, and Hearns. Duran/Mayweather is a pick-em fight at 147. At 135 Duran wins hands down. At 130 a prime Arguello would take Mayweather out late in a 15 rounder. PBF is p4p #1 in the world right now, but he is a far cry from the best ever at any weight he has fought at. Boo