Mormeck was a very good cruiser in his prime, but I don't think he would fare well against Hearns IMO the problem is his defensive style, at first he can slip a few punches by bobbing and weaving but he is not consistent with this and quickly resorts to a weird turtle shell style (probably because it is less demanding stamina-wise). At this point he just puts his left hand close to his face and accepts to be hit. I'm sure he'd be target practice for Hearns In his prime JMM had decent mobility to serve his pressure fighting style but I think he wouldn't be able to corner Hearns at any point, the Hitman's footwork is just too good So IMO if we can't hit Hearns and if he's here to be hit that's a late KO for Hearns. Mormeck has a decent chin but if you hit him square you see what happened with Bell and Haye My two cent
It's hard to tell. Hearns is not a natural cruiser and and fought very little at cruiser until very late in his career. 90% of his best fights were under 175 pounds. Considering all of this Mormeck may have a slight advantage.