Undefeated I rate Calzaghe higher than most but let us be real here. The better question is how does Joe do against Ward's resume.
He already beat Kessler, Joe's best win without losing a round. Ward would beat today's B-hop without a doubt. To much energy and too fast.
"I'm not looking for tough fights" -- prime Joe Cal "I know my limitations" -- prime Joe Cal when asked about RJJ. "It would take the crown jewels" -- prime Joe Cal when asked about RJJ. There's no way in hell Joe Cal would have entered the Super Six, especially not as green as Ward did. Even if he would have accepted an offer, No Show Joe would have had a "hand injury" before his first test. That said, I would favor Joe in each of the fights Ward has won.
Actually that is one of the rare cases in boxing where Bika got noticeably better the couple years after the Calzaghe fight. He was better on and post-Contender than he was pre-Contender.