Russ,
I thought of that when I had the same problem but there is nothing like enough meat around the threaded hole to drill it out to accept the threaded rivet. Plus, the threaded rivet won't be the right thread for the special "screw in a screw" that retains the headlamp and bezel.
The only solutions are to "bodge it" with some epoxy or something similar to close up the rusted threaded hole, braze a suitable nut on the back if the metal will take it or, utlimately, braze on a new tab completely. The latter is what finally got done on my car last year.
I noticed you'd got a slew of replies on Rennlist - it's obviously a really common problem.
Good luck.
Regards
Dave