273 swap to 318/ build, cost, potential, daily driver

you can probably add 350 to the machine work bill on the heads for new hardened exhaust seats, and probably a guide or three, and unforseen things and stuffs. a new crank isn't all that difficult to source, so the cost of that (free~$150) + whatever they need to do on that (hopefully just a polish). then cough up $700(?) for pistons and rings, plus a bore and hone at i'd guess another $400 unless you can get away with just a hone and rings. if the rods need resized? there's another $200.

double the price on the waterpump and timing chain to get actual decent parts that will last.