Try a PCV valve from a late model engine of about the same displacement as your engine. An EV-98 from a Ford 289 / 302 is probably a good choice. Remember to include a filtered breather vent to allow fresh air circulation throughout your crankcase. This will greatly increase the life of your oil as it will purge the corrosive compounds formed as a byproduct of combustion. Put the PCV at one end of your valve cover and the breather at the other end. Or use the existing crankcase breather location. Good luck.
