I would:

1. Run a bottoming tap in it to get the threads as close as possible to bottom.
2. Locate a bolt with thread length equal to or greater than that in the pc. and chamfer/square up the end comparable to the tap to insure bottoming out.
3. Dip it in green loctite (bearing retaining compound)before torquing it in 25-50 ft. lbs.
4. Mill away the remaining bolt head/shank.






1952 1300 Canadian 1/2 ton restomod
You Tube