Hearns would beat his ass, and after that, feed McClellan to his own pitbull. Seriously though, Hearns probably outboxes him to a wide UD.
Either Gerald KO's Hearns in the first five rounds or Tommy boxes his ass off and wins either by wide UD or late T/KO. I'm leaning towards Hearns, imo he was undoubtedly the better boxer and talent but G-MAN could be a seriously bad matchup for him. Actually, more I think about it the more I lean towarda G-MAN. He didnt have the talent, ability, or skills to stand there and box with Hearns at range, I think this plays out and ends like Hagler-Hearns. Straight caution to the wind, balls out bomb fest, and in that type of fight -- which Tommy could always get dragged into and could rarely ever turn down a war, McLellan leaves Hearns out cold with his eyes open on the canvas in one of the greatest 3-4 round fights in the history of boxing.