I grew up on Oahu...Kailua to be exact...
I also have a pre-dye carter buzzard...I got it new around '96
carter sells the entire bolt/hammer assembly that includes just the bolt, hammer, and hammer spring. He also has 'powertube' assemblies...these include a new cup seal (at least they did the last time I purchased one in '01, not from carter but rather from central paintball). He should also be able to supply a new pump spring.
as for the set oring you mention on the bolt...this is actually a -112N90 oring that has been turned to fit properly. I was able to replace mine by chucking the bolt with a fresh oring and holding, with light pressure, a small peice of sandpaper to the oring as it turned.
Hope this helps...I recently tried to contact carter machine to buy a new bolt/hammer set and they flat out ignored my request. You may want to act like you are trying to purchase one of his expensive pistols in order to coerce them into calling you.