Had asimilar issue with some of the bits & pieces for my beastie. Took some time but I found nearly identical new parts that fit th bill.
Pull the valve offand go see your local hardware stores and places like Napa, you may find something similar that can be adapted to fit and still look like the original.


1956 GMC 370 dump " 'Tater "
1970 VW Volksrod "the Black Bomber"
2007 Chevy Avalanche
2020 Jeep Cherokee Trailhawk,
2005 Harley Davidson FLHTCUI

I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion!
:P