Sounds like you have a running drivable 318. You could have that motor in and be able to drive and enjoy your car while you build your replacement motor. You have a 360 block and 360 heads. If you are planning on boring the 318 and replacing the pistons you could do the same to the 360 at the same cost. You would need to come up with a crankshaft and rods. They could be found from someone doing a stroker or elsewhere.