Below is an ILL of a PCV SYSTEM as found on a later LT 4V application -
The pan must have a splash shield/baffle under the vacuum intake source (several styles of pans)-
The fumes are drawn into the adapter/separator (6A665) and then cooled in the tube (6758) where excess fumes drain back to the separator. The PCV valve is installed far from the vacuum inlet to help prevent contamination.
If one cannot find this system, either NOS or take-off, one must fabricate.