there are a few ways, what i have done is eliminate the valve, removed and plgged the hole foe the black box, run 2 lines from the back of the block to a vented can, and added a 3rd lime underneath that tee's into one of the output lines to serve as a drain back.
what u want is to vent the prusse but oil comes up with the fumes, the fumes exit the can via the filter on top and the 3rd port returns the excess oil back into the engine.