Calzaghe UD. Calzaghe has a great chin, and took the punches of Eubank and Lacy without flinching, and even when he did get stunned or knocked down (RJJ and Hopkins) his recuprative powers were amazing, he's not getting KO'd or TKO'd imo. I see McClellan getting in some great shots, maybe getting a flash knockdown in his favour, but Calzaghe would get right back to work and outhustle him to a relatively close but clear UD.
McClellan was a freak, that dude could knock you dead with a single shot. Cal would have to avoid that first round knockdown **** with McClellan. Joe needs to slap and run all night long to win a decision.
Who were the big punchers that Calzaghe faced? Gerald would land something big and finish him in my opinion. He was hurt by a shot Jones and an old Hopkins, both early, Gerald was a very quick starter and i see him doing damage. If Joe stays out of his way early and doesn't let his pride get the better of him he would win a decision, big if.