Kurt,
I already replaced all the seals on both my valve blocks recently, including NRV o-rings & diaphragm valve. The only original parts remaining are the valve plungers & their springs and the NRV's themselves.
NRV-1 seems to be sealing ok, because when tank feed is pressurised, the only escape is past the Inlet & Exhaust valves. The other two NRV's only control the flow during air-bag inflation or deflation. There's some slight wear on the cone tips, so used the best one for NRV-1.
If you have valves with new rubber for better sealing that would be good ? I have done the refacing with emery on Inlet & Exhaust plungers on one block, and it seems to have held pressure for 48 hours, so better than before.
Pete
Tried that when I first bought my car. Then thought f*ck it and got a block off Kurt. 2 actually. One is still in the box in my shed somewhere.