Just saw your post. Doubt you are still looking for this but I have some as part of the Aeroflash 156-0039 kit.
I have a parking Brake valve I removed when I installed the Williams Conversion. Removed from a 1960 PA-22-160 Also have the Under seat mounted Scott Master plus pedals as removed.
I just bought one from spruce aircraft supplies which is the scott valve 4200, that is what came off my PA-22-150. The difference between the 2 should only be the fitting size.