Im pretty sure year one has them in there catalog. Or you could always pull one from a pre 73 parts car.o No:
Here's a source: http://www.broachbuster.com/id49.htm I'm not sure of his claim that they will work fine with both refrigerants, though. POA valves need to be adjusted down a bit for R134a. www.classicautoair.com also has them but they don't show a price on their website. You can also send them a used valve and they will test and adjust it for you.
There ya' go. A used valve from carmantx and a trip to classic for a freshening up, and you'll be in business.:beers2: Although POA valves do fail at times, they aren't a high failure item. I've pulled a lot of them from jy cars and they are ok about 80% of the time