You might want to post over on the Tinker's Guild (if you haven't already). I know plenty of folks there bought some of those bodies and built perfectly functional guns from them. Actually the first run of "Fastback" bodies were made from those, IIRC. Maybe there's one particular valve that works better in there than the others.
I know I had problems getting the valve to line up with the set screw, but once it was in there, it worked fine. I ran it for a few months (before getting the body anodized) with a Palmer LT valve in there and never had any leakage issues. I think I still have that valve around if you want to try it in there. It was otherwise employed when I got the anodizing done, so I put a stock valve in there since I had a bunch of them at the time.