Way back when, I found a fitting with a male 10/32 thread and female 1/8" NPT somewhere online. I can't for the life of me remember the name of the company I got it from, but I know they exist. The other alternative is to have the valve drilled & tapped to take a 1/8" NPT fitting directly. From what I've heard, this can be a bit tricky due to the thinness of the material, but there are plenty out there like that, so it's possible. FWIW, PPS sells a 10/32 to microline fitting, but it's allegedly only good up to 300 psi. Unless you're going to regulate your input below that, I wouldn't try it.