Drill and tap the oil galley plugs?? Really?
I was an idiot and didn't put in the plug at the back of the valley, and I had no oil pressure. But I doubt these plugs would pop out, could but the probability is not that high.
There is a reason Dart and World blocks come with them tapped from the manufacturer. Actually pretty standard procedure. I do it on every performance engine I build.(5-6 per year) Takes less than 10 minutes per hole, and you never have to worry about them again. You would be surprised at the number of press in plugs I have seen push out. It's cheap insurance, only takes a few minutes per hole, so why wouldn't you do it would be my question.
They can be done without drilling, just tap. The 3 behind the timing cover are done with 1/4-18 npt. The one closest to the distributor gear needs to be tapped deep enough so the plug doesnt interfere with the distributor gear and this means the tap enters the lifter bore, make sure to clear that lifter bore.
For the record, not trying to come across like a "know it all". I read these questions, and I am just offering suggestions I have gained from real world experience. My Dad owned a garage and drag raced, I owned a small chain of garages and drag race. I have just been exposed to a lot of this stuff over the years, and trying to help, if I feel I can.