Calzhage can run but can't hide. Fosters jab would counter Calzhage's foot movement. Sooner or later (Probably sooner) One of Foster's hooks finds it's mark, and Calzhage get's the full 10 count.
I would only add that Foster is fully capable of KOing Calz with a right hand. It's a misconception that it was just the hook. Foster had fight-ending power in both hands.
But most of his real viscous ko's came off the left hook. But yes I know he was capable of putting his opponent to sleep with either hand. Saw him fight many times....
My prediction is that Calzaghe might last late before getting stopped if it's an older Foster. Against the peak Foster who KO'd Tiger, I struggle to see Calzaghe going more than 5.
Joe was a great fighter but he was reachable by a right. He was also dropped by Bhop at 175 and Bhop had 0 kos at 175. Foster fists were dynamite. I doubt Joe makes the final bell.
Calzaghe was a fantastic fighter. Tough, as well. But he can't best Bob Foster, over the course. I think it could go a bit like Foster/Finnegan with Joe beating the count, but being in no condition to continue.