Brian Capp is the aficionado around these parts. He makes a business of restoriing O2s out in Northbend. He will sell you parts, but you usually have to go pick them up and he seems to prefer to do the work himself when possible. Ie, you drop off your car and pick up a nicely restored one sometime later - like any mechanic shop really.

I haven't contacted him in a while, but his info used to be

Brian Capp NW 02 SIG Chairman
M-ten Autowerke
tel 425 888 4002

Another source for great parts and good advice is AutoSport, in Seattle. You need to pay top dollar but these guys really know their stuff and are very helpful. I consider them to be one of the premeir locations for machine shop work. When they were redoing my block I noticed their shop was full of blocks from ferraris and jags and some cars nearly 100 years old.
Fun stuff.

Hope this helps. Feel free to email me at
sean_harris@hotmail.com

Good Luck!