depends on what needs rebuilt? if u already have pistons and rings to go into it and just need everything put back in and are able to use ur current connecting rods and crankshaft and dont need anything done to the valve train, then ur just gonna have to have a new head gasket put on, new fluids replaced, cylinders checked, if need be rehoned and deglazed, probably just 400-500 bucks to open it all up and figure out what u need if need be u can be looking at 1000's if alot is needed, just depends on the condition of ur engine, and engine components. sometimes its cheaper to just get a new engine block all together.