Most machine shops won't want to sit on an engine too long, as that costs them $$ as well. Some shops will even reserve the right to sell an engine if the owner doesn't come to pick it up and pay for services in a reasonable amount of time, say 30 days. You'll want to talk wiht the shop first to see about making arraingements for the work you wnat done, they'll probably work wiht you seeing as it is a somewhat odd engine. You'll probably need to call around to find a shop that'll even touch it.
I can't really give an acurate range for a Fiat 4, but my 235 came in at a little under $500 for the machining, that included cleaning, magnaflux, boring, polish crank, 12 new valves installed, rods/pistons assembled and fitted, and cleaning all of the tins and bellhousing, plus resurfacing the flywheel. That was about 11 years ago.
