PVC Valve

Surly there is still some NOS Novo 117A98 PCV valves out there. I would of figured there were millions of them manufactured. I've found a couple of used ones, (I already have two old ones) on the internet, but I would like a new one. I could adapt a newer type, but I'm trying to maintain some "fidelity" to my restoration. The Novo 117A98 PVC is threaded and held in place on the cap with a PAL nut. Any Ideas?
Norm