Engine build up options

360 all the way. You've got the cubic inches over the 318 and you don't have the big block issues with exhaust, plug changes, extra front end weight, etc. If the 318 is already running in the car, leave it there while you build up your 360. Put in something like a .030 over KB Hyper 9.1 CR piston; have a good valve job done with maybe a cleanup cut on the block and the heads; an aluminum intake like the RPM Airgap or old LD340; Carter, Holley or Edelbrock carb in the 650 cfm range; something like a Comp 274 or 284 cam, lifters, and related spring set; electronic ignition with the advance curve reworked; and a good air cleaner. Have the tranny rebuilt; something in the 2500+ RPM stall converter; and a 3.23 or 3.55 rear end, and go have some fun. This is just MY opinion of course. :)