Or you could just drill and tap for 8-32, but only tap three or four threads deep.
Then just use brass 1/8" long setscrews and drill them yourself to the desired size. You can get 50 or 100 from McMaster-Carr for the price of one pretty air bleed, and not even have to countersink the hole scope
Worked fine on my 4780 carb, anyhow. wrench