Gas Thread BSPP and American thread NPSM
I do have a part that need to match the ASME B1.20.1 (NPSM), so it's a straight thread, but it need to match the ISO 228-1 G as well for Europe.
Is there a way to get only one thread that will work in any case?
If the threads have the same pitch, then you might be able to get them to work together, but the result may be too tight on one, and too loose on the other.
If you can find specs on both profiles, sketch them up, and overlay them on top of each other. It should help to visualize how closely the profiles match.