Blocks and internals the same?

Chances are the crank is cast, but that means nothing to your buildup. The J jeads are a good addition, but I'd suggest if you can swing them, a used set of Magnum heads. They will feed a 318 very well, I would not suggest doing more than a competittion quality valve job..it's very easy to mess up the high velocity these ports have factory. Using a flat top piston will give good squeeze, and a modern detonation resistant chamber, plus seats that will last on todays ether. The heads will need to be re-drilled for the std intake pattern, and you need to run AMC lifters and pushrods that are drilled for oiling, but you get 1.6 rocker ratio, plus the other benefits. That's just a suggestion..The J heads should be cc'd and either the block or heads milled to get a good compression, then make sure the rocker geometry and pushrod length is good. You'll need pushrods..