The head gasket I mentioned is the thinnest head gasket you can buy anywhere.

My thinking about compression ratios is the stock MOPAR open chamber 8.5:1, 302 heart-shaped chamber 9:1, aluminum head with closed chamber, 10.5:1.

I don't know what heads you are getting for so little, they must be ProComp/Speedmaster. These are starting to pick up support as quality of the castings seems to be improving. They are sold in pairs, most of the other heads are sold each. So Edelbrocks will run you around $1400. The heads should have the stem clearance checked and the valve job checked before you put them on.

When you do this, I think the KB 167s are the winner. They're a lot lighter, which will make the engine more responsive, and they optimize your compression ratio and squish. The 30 over 318 is 661.6cc, to get 10.5:1 compression, 661.6/9.5 = 69.6cc above the piston The valve notch is 5cc, the head gasket and down in the hole volume is 8.6cc, adds up to 13.6cc. 69.6 - 13.6 = 56cc which is the ideal chamber size. Speedmaster smallest head is 65cc. 65+13.6 turns into 9.4:1. It'll run on Regular, maybe midgrade.
The 814 slugs would be somewhere around 8.3:1. That's nowhere.

This engine will sing. High flowing heads, lightweight pistons, decent compression, all factors that help the engine feel lively. If you had an extra $275, a set of aftermarket connecting rods could take another 100 grams off each piston/rod combo. Hey, I'm going to work you into a $3000 engine if I'm not careful.

One nice thing about the KB pistons, they require a larger end gap on the top ring, so you don't have to try to find 0.005 oversize rings so you an file fit them

American gearheads who are used to the old V8s don't realize that with good flowing heads you don't need a lot of intake duration. I'd stick around 210 at 50 lift.

Don't hesitate to PM me with more particular questions.

R.

PS: A Magnum type head would solve some problems, 58cc chamber.
PPS: The skinny 318 rods weigh in at 726 grams, the fatter 496 or 645 rods a portly 758. I believe your engine still had the skinny shank rods.