I put a literal rubber stopper in the dip stick tube because the bottom of the tube sits in oil so crank case pressure would push straight oil up the tube. On the fill tube, I put a used a grommeted breather cap that has a hose end, then ran that hose to a catch can as well as just venting the PVC port straight to the catch can. On my build, I put extra baffling in the oil fill tube and next to the PCV port to catch/baffle oil before it vents. In the fill tube I literally took a sheet of tin metal, rolled it up so the ends would be like 1/2" apart when sitting in the oil fill tube and slide it down to the block surface with the 1/2" gap facing outwards.

Randall - I have a dual turbocharged OHC6. I am having trouble with crankcase pressure. What did you do to stop oil from leaking from the oil filler tube or wherever?
Thanks.
Brad