...BTW your Bieber avatar is awesome.-Malone
If nothing is wrong with the pressure regulator and if you are certain all is well with the headgasket, I'd put in the cheapest sythetic oil you can buy (I wouldn't even buy diesel rated stuff unless it was cheaper) and see what the cold pressures are. The other thing I would check is to pull the injectors next to the oil feed passage and see if they are covered in oil. You might be pressurizing the oil system with combustion gasses.
Post a pic of your head. I had an 85 built car ME that was hydro. VW never was one to do something simple.I bet something amiss with the HG or Head itself. It maybe needing pressure tested.
I meant to say the head gasket was for a mechanical head. My mistake.