Engine is pulled - 273 rebuild or replacement 360 crate?

If you bore the 318 .030 over, it will work out to 349 CI. Put some decent heads on it so it will breathe and a good dual plane intake. With that cam, it should run pretty good for the milder sort of motor it will be. The 650 AVS2 will be plenty, but buy you a kit to tune it so you can optimize it to work with the rest of the motor.