excessive 340 crankcase pressure
Where are you pulling fresh air into the engine with that set up? Adding another valve does nothing. You need a breather on one side, the PCV valve on the other and let it pull fresh air into the engine and out through the PCV valve. That's how it's designed to work.
If you are trying to use the PCV system to pull a vacuum in the crankcase, you can do that. Two valves won't help. It also won't work if you have excessive blow by. I'm all for getting a depression in the crank case. But you aren't doing that either.
Did you ever do a leak down test? If so, post up what you found. If not, you need to.
