What cam would you buy?

IMO keep the cam, swap to a good duel plane intake, swap in some 3.55-3.91 gears, don't worry about the carb the 670 would be one of my top choices. I think your combo would come around to your liking if these two things were done. If not, then swap the cam. Nothing worse than a low vacuum having torque killing big single plane coupled to ridiculously high rear end gears.