A fight like that can only end in a TKO/KO. Both are simple bangers. Although id give Lavar the better edge with the hands which isn't saying much.
I would also give Lavar the edge standing, but not by a whole lot. I would probably pick Carwin to win, though. As much as I would like him to just stand and bang, I think he would be smart enough to take the fight to the mat, and I doubt that Lavar would be skilled enough to get back to his feet. True.
Speaking of those on PED's, Wasn't Krystof So-whatever-inski was previously a 300 pounder and was a body builder?
I think Carwin would crowd Lavar against the cage like he did to Mir and pound away from there for the KO. Use your advantages, which is short powerful punches in close.