The man who comes to mind for me is Wilbert "Skeeter" McClure. He was one of the most accomplished amateur boxers out of the US winning a gold medal in the 1960 Olympic team along with Muhammad Ali and Eddie Crook Jr. Skeeter had a decent pro career fighting Ruben Carter twice (one draw, one contraversial dec. loss) he was also twice on the losing end against Luis Manuel Rodriguez, but he was a great fighter in the amateurs.