Personally, I usually leave that plug behind the distributor, a press in cup plug. Considering the challenge of tapping that hole correctly, without going in too deep and having the pipe plug protrude into the front lifter bore, or not deep enough , and it interferes with the distributor body, not to mention it is at the end of the lifter feed passage, so the oil pressure is likely lower there, I feel any potential benefit is outweighed by the potential problems. I can say that I have never had a properly installed cup plug in that location ever leak or fall out, in close to 50 years of playing with FEs.