I ordered the new seals from: www.theoringstore.com
I ordered seals made of V75 Viton after reading about that material's properties on the store's website.
The small seal is 2mm x 8mm V75 Viton O-ring Black Model: V2.00X008 -- (2mm thick, 8mm inner diameter)
The large seal is 1.5mm x 31mm V75 Viton O-ring Black Model: V1.50X31 -- (1.5mm thick, 31mm inner diameter)
I believe that the smaller seal in the Blunt kit is 1mm x 8mm -- (1mm thick, 8mm inner diameter, not sure of the material it's made of)
I use these O-rings AND Blunt's kit. The stainless shaft in Blunt's kit is well worth the price vs. using an original with the plastic shaft. Unless you have a valve that has a brass shaft in good condition. Some valves had brass and later switched to plastic/nylon. That goes for the internals too. The all brass valves are nice. Then you just need the O-rings, new screws and the star lock washers. I've never been able to remove the old screws without destroying them. Had to tap them and use an easy-out.