Mildly modified 318 PCV valve selection

It's not the cam that wants 20* it's the compression and cylinder pressure. That 318 is an 8.5:1 motor at best. Coupled with that camshaft, and your cylinder pressure is lower than normal. This is the reason it wants so much timing. Pull the timing up and leave it there. Does it run good there with no spark knock? Yes? There's your answer. All the forum geniuses in the world cannot tell you what the engine wants. It will tell you itself and is trying to. The PCV system is normal and fine. Spend time worrying about something you're really having trouble with, because the PCV valve and the timing ain't those things. You clearly have the timing figured out. Didn't the vacuum signal increase when you pulled initial to 20*? There's your evidence the engine wants the increase in timing. Just remember to keep the total limited. You are going to have to play around with that until you find the sweet spot. Some like 32. Some like 36. It all depends. As long as there's no spark knock, it wouldn't bother me to see close to 40. I never worry too much with total as long as there's no spark knock. Good luck.