I run a factory style PCV valve on my 63. Been using it since this eng went in my car in 2011. Its mostly a street car as I only race once or twice a year but its never spit any oil at the track. Course the other valve cover is a brether and I even consider just using a breather in both covers at the track like in the old days but as I say its been fine with what little racing I do and on the street. Ron