I had no luck keeping a pair of breathers on the valve covers from putting oil everywhere on my 572. Tried different styles of breathers, baffled fittings, even wire mesh in the tubes, extending the tubes, etc.
I put a vacuum pump on it and it works good, but in hindsight I'd just run a pair of -10 lines, one on each cover, to a breather tank and call it good.

Sounds like the threads on that one cylinder are a little rough or sharp at the top causing the plug to be a pain to start. I just use a long extension and they thread in pretty easily.