Best 318/x-head /hyd cam combo

That's why I suggested the KB slugs for zero decking with the open chambered head.
I wouldn't worry an inch over having to much head with those X heads.
Though I suggest a bit more cam, a good bit. Look at a cam of at least 230*'s @ .050 or larger to run in the mid 13's.

My cam pick would be the Lunati 304A3 (AKA 10200313)
276/284 (231/239) - .514-.536 on a 108/102
2800-6500 rpm

What intake, stall converter do you have?
What size tires?