This is for the plunger ends which you can't buy. The NRV orings are included in any kit so those are easy.
I'm pretty sure silicon spray or grease is fine for the viton orings. The valve block I just replaced from my car was rebuilt in 2012 and lasted up until last year so the silicon grease and spray I used during that rebuild obviously didn't damage the orings I fitted back then too badly. Besides, scuba guys use silicon grease and spray all the time on their equipment.
@kurtjohnson10 can supply new nrv's,don't know if he will send them to KL.
Petroleum based vaseline might be a different story, but I've only ever used silicon.