Best 318/x-head /hyd cam combo

Since your rebuilding the 318, you'll need to grab a quality piston. Low compression can be an issue. It is not the end of the world. The bigger the cam the more compression you should have to operate the cam as intended.

You list the lift of the Comp Cam, but not the duration.
(Problem)

If your looking to up the compression for the 318, look to the KB line of pistons. They have slugs that can be used at zero deck height in Hyper or forged.

When it comes to the cam, the Purple cam has a duration @ .050 of 248*'s.
You now can look at other cam companies offerings in this duration range.