For a restoration - and to go into a '57 Chebbie, and all the numbers match, it might be worth picking up but will still need to be torn down for inspection and new gaskets/seals at a minimum. Or it might need a complete overhaul, including valves and pistons, a crank grind, etc. Then you are talking the price of a NEW crate motor. For a street rod/machine - there are better Chebbie choices