If the threads are damaged on some of them, then drilling and using pressed in studs may be a better option. I just thought if the threads were fine going with a screw in one would save a bunch of work and time.

Those things said..another issue to think about that just came to mind, since they were originally made to have the wheel bolts and nothing would ever haved to seat against the back of the hub/drum.. the flat face on the back side you can see in the picture.. if you did drill them out and use a press in stud, you need to make sure the face of the hub is perpendicular to the hole. If not when you press the stud in, it might tend to want to tilt somewhat to make the head sit flush against the hub. Depending on how thick the area is the knurling will have to hold it straight.