I had that problem with nitrous in my 357w on hard pulls. Dipstick pushing out, blowing oil. what I did was welded bungs in my headers at an angle and ran a hose to the valve covers/breathers to help evacuate cc pressure. not exactly emissions friendly but it did the trick....
I had the same problem after installing my turbo kit. I am still using the stock valve covers and utilized a breather in the place of the oil cap. Its basically venting the extra pressure into the atmosphere, but stopped the constant ejecting of the pcv valve (and oil leak) from the back of my intake. I am still working on the method I will use for the next motor, but am thinking either a dual breather setup or a catch can style recirculation.
most likely that small nipple on the breather is not enough to reduce crankcase pressure. You can try using what you have with an open breather where the PVC is OR you need open breathers on the VC's OR a VC breather like you have but a 5/8 - 3/4 outlet nipple going to a catchcan with an open breather on top. (or an evac system like previously mentioned)