What can make this fight interesting is that Chad is naturally an orthodox fighter but fights southpaw in honor of his father. If they fight, will he switch? How would that play out?
I'm taking Dawson. Dawson's size combined with just enough speed and power and Calzaghe's age and the extra weight slowing him down a bit gives Dawson the edge.
His boxing IQ isnt that great. His best win is against Johnson and that is highly disputable. Johnson pressured him all night and Dawson struggled a good deal against him. His flurries are what won him the fight but they werent exactly effective nor accurate. It was more the illusion of effectiveness that got him the decision. I think Calzaghe would simply confuse the hell out of Dawson with his angles and hand speed. Just because Dawson has fast hands does not mean he can match Calzaghe punch for punch. Dawson has a conventional southpaw style whereas Calzaghe is just a awkward fighter for anyone to face and Calzaghe has the reflexes to match Dawsons and the superior ring generalship along with the footwork. Calzaghe also has the stamina to sustain an attack all 12 rounds and would take Dawson to the edge more than Johnson did. Dawson got tired in the later rounds against Johnson. He wasnt gassed but he was obviously fighting at a faster pace than he would have wanted. Calzaghe UD. I am sure Chad would have his moments, but I just see him being confounded by Calzaghes hurricane all angles style. He would be firing off rapid combos but he doesnt do anything that particularly troubles Calzaghe. So he has fast hands, Calzaghe knows how to duck and catch punches. Calzaghe would be getting the better of him and in the later rounds when JC is still going and Dawson is tired he would be like Kesseler and Jones where they just look confused as hell as what to do.
I'm going to say Calzaghe wins this easy. Dawson is getting to much credit for that win over Tarver. Tarver is pretty shot himself. Calzaghe UD. Only one man can beat him at light heavy and his name is Bernard Hopkins.