I think I have a similar issue and, like you, I believe it's oil coming through the PCV. I think I have bad valve guides causing the problem to be worse than normal.

Sometimes I'll get a bit of smoke coming out the valve cover vent. I know I need to get my head rebuilt. I believe the valve cover area is being pressurized because of a leaking valve guide/seal. Using stock seals and I don't think the heads were ever set up to take new, lead-free gas.

It's on my to-do list.

I notice it especially when I run the car hard.