Bud is better at 168 than SRL, Hearns and Duran were, he's also better in his late 30's than those three were. Bud would have toyed with Barkley.
Barkley gave a prime Nunn who was a very talented slick southpaw 6'1 with a 77 inch reach all he could handle. So no Crawford wouldn't of toyed with Barkley who wouldn't of just sat in the centre of the ring like Canelo barely throwing any punches Barkley would of really pressured Crawford and forced him to fight.
Canelo is far better than Barkley was and harder to hit, Nunn was just running and slapping vs Barkley it was a horrible fight, Bud would have landed more power shots than Nunn did and thrown more counters, Nunn didn't counter well vs Barkley and Bud has more power than Duran did at the higher weights and yet Duran floored Barkley while Nunn couldn't, Duran stood in the pocket and landed more power shots than Nunn did which is what Bud would have done too, plus Bud could match Barkley's reach and had a much longer reach than Duran.
I'm going with Duran, SRL and Hearns at 147. Competitive but losing efforts by Bud. At 168 Duran is a fatso, Hearns is vulnerable. SRL is also not competitive. Hagler wins.