Check valve for p-valve

[skdvr]

am looking to make my own p-valve for another DS that I have. I want to make it balanced so I need a check valve. I have Vance Harlows book on DS repair and was going to follow the instructions that he has, but the check valve that he reccomends (well the pt number he gave and place to buy from) but they have minimum order of 25and I am not going to build that many p-valves. So have any of you made your own balanced p-valve, and if so what check valve did you use. I found some at usplastic here and here I just am not sure which would be best, if they would work at all... Does anyone know if the .5 crackign preassure would be OK, or would that still be to stiff.

Anyway, just looking for your experience if you have any with DIY p-valve

Thanks
Phil