Just my observations from over the years: Pits in the crank where plain bearings ride are usually not a problem if the crank is simply cleaned up enough to remove any high spots of rust. Pits where needle bearings run can be okay as long as you can't catch a fingernail in them or if they're not across more than half the width of the surface. It WILL make for a noisier engine, though.
Getting a machinist to do anything around here can be absurdly expensive. I just had to pay $80 to have two slots put in a shaft for a pair of 3/4" woodruff keys. He is the only guy on Cape Cod that would even DO it.