When you consider the size difference, it's only fair to make a compromise: I would have them fight at 140 Could Hearns make the weight? Yes of course. As a welter, he often weighed in at 145 or less, and he said he had no trouble making the weight. When he'd was about 18, he fought at 132 where he was ovewhelmed by Pryor. At 140, Hearns has more muscle than at 132, but not as much as at 147, so he's less likely to take out Pernel with one punch, and if there is anyone who can outbox Hearns, it's Pernel. If they ever fought at 132, Pernel wins easily.
If there's ever a boxer ALL wrong for Whitaker it's Hearns. And theirs many reasons why. Most important one is Whitaker wasn't a great welterweight, and was slightly to completely over the hill when he fought at there. Second most important reason is the sheer size advantages for Hearns 6'1 compared to Whitakers 5'6" a 78" reach compared to a 69". Hearns matched up favorably with Whitaker with speed and skills especially when considering how he used his usual size advantages. Look at all the problems Trinidad and Hurtado gave Whitaker. Put Hearns in their place. Especially against those versions of Whitaker. This fight has Hearns fight against Duran written all over it. Whitaker maybe able to frustrate Hearns awhile longer, but that's about it. Hearns possibly best jab in the history of the welterweight division would be key. It would keep Whitaker at Hearns preferred distance until the right hand finds its mark. Fights over with in 7-8 rds..... And I'm being generous. Hearns all wrong for Whitaker at welterweight.. .