I'll again suggest New England Custom Guns in NH (check out their website) - you could even make a nice day trip out of it and drive the gun up yourself and talk with Mark the master smith. They are very close to the Precision Museum in Windsor V T where interchangeable parts for guns were first developed. Lots of early gunsmithing stuff in the museum.
Griffen & Howe in NJ - they also have a gunroom in Greenwich CT where no doubt you could drop the gun - I have never used them for repairs, perhaps others here have.
