I have tapped them out to 1ba (I think ) in the past , but a better fix would be to get a nut or square piece of steel that fits in the trigger cage, brazed or whatever in the inside of the cage and tapped back to original size.
Someone told me that the stock screws on Hawks etc are a special self tapping screw!
If someone has a lathe you could get a small top hat made and then fix that in the hole and tap it. I guess a bit of tube , welded and threaded would be ok if you could keep it straight.