How do you test old style pcv ?

I always just pulled the valve assembly out of the valve cover with the engine running, stuck my finger over the hole in the end of the PCV valve, and it it went "thunk" and the idle dropped a bit, it was good enough. If you had the wrong valve that allowed too much vacuum, you'd also have a rough idle. That might be tough to determine if you have a performance cam with very little vacuum to begin with. You may have to run a full compression/leakdown test to make sure your engine didn't just develope a problem.