I think you used the right term to start with. A good machine shop should be able to work an just about any engine brought to them.
Doesn't require any special tools to line bore, do a cylinder bore, press on new rods for these old V-6s than for the inliners or later model engines.
The difference may be they don't have the knowledge to use them. But that shouldn't be a problem either unless the shop doesn't have any books with the specs in it to start their measurements with.
There is a man here in town that does machine work and he is in his 70s now. Does just about everything from new cam bearings to sewing up a crack in the block. He bores blocks, sleeves them when needed.
About the only thing he doesn't have the equipment to do is line boring.
So perhaps finding a GOOD machine shop should include knowledge of how to work on these old engines. They really aren't that hard to work on.
