Any chance of the new PCV installed backwards? They act like a check valve and only flow one way - easy to do if its the type installed in a hose, but most can't be done backwards as one end fits in a grommet.
Spacer plate under the carb? Could you have connected the hose to the fitting for a water passage? (I'm only familiar with Bullet Birds and they have a water passage in their spacer. Perhaps 58-60's don't?)
Posting a couple of pictures will help.