Just make new ones out of drill rod and harden them, then temper in an oven at 400F for an hour and leave them in there to cool real slow. Even an annealed alloy bolt should work for donor material if you don't have drill rod or a broken drill shank to anneal and work with. Trying to grind a circular, concentric, cylindrical hole in a hard piece of metal that's difficult to indicate true in the first place is not my idea of the best approach. On the lathe you'd finish the thing completely in one chucking operation and then part it off, deburr it, and heat treat.