The factory studs are swaged in place after insertion. The CSM tells you to use a cutter tool to machine this swaged part off BEFORE pressing the stud out. Obviously your shop didn’t do this, which is why the hole is now oversized. Simply page through the Dorman catalog and you’ll find studs with larger splines that fit the oversize hole. I did this on my 62 when I converted the driver side studs to RH thread.
It’s pretty easy. Remove the brake drum. Remove the four nuts that hold the retainer plate to the axle housing flange. Slide the brake drum back over the wheel studs with the open end out. Loosely install some of the lug nuts onto the wheel studs, flat side towards the drum. Now use the drum as a slide hammer to pop the axle shaft out. Now is probably a good time to change the axle grease seals also.