Hey Mick,

The PVC is a controlled vacuum leak. At idle, vacuum is high (theoretically) and should keep the ball closed. When you mash the throttle, vacuum drops and the ball goes loose. This is where most of the blow by/crankcase pressurization occurs and forces this stuff up the valve covers and back into the intake. When the engine is off (no vacuum) the ball should rattle around.

Now, if your cam has alot of overlap which results in low vacuum, the ball may not close down acting as if you were at a wide throttle position. If you have a baffle under the valve cover, there should not be much oil going into the PCV. If there were, the hose should have oil in it as well as the intake. Also, where do you have the hose connected to? It should go on the carb. If you connect it to the intake, the nearest cylinders may go a little lean.

I know alot of guys just run two breathers and no PVC, but if it were me I'd like to have some sort of positive venting system for the crank case like an evacupan system (running two hoses to the headers and letting the exhaust gas create a small vacuum)

If your tail pipes are clean (no oily goo that looks like a two stroke), then I would suspect it's more likely an intake/head seal problem unless the oil rings/second ring fell out or you are using low tension oil rings. With as little miles that you have on it, I doubt it's a ring issue.

What was the piston to wall clearance? Has it been doing this since it was built or just started recently?

The 69 and under valve covers have unique issues since the breathers fit onto stacks (more of a problem for the PVC). Tony D'agustino sells a nice repo breather but they are about 100 bucks. You might find a Chivey breather the might fit but the PVC you'll need to find from a repo place. Mopar used to sell them but I find fewer and fewer parts are available from MP. And yes the stacks do seep oil. The thinner the oil, the worse it is.