Not a A-body but a couple of questions about a 318.

More than likely I will just use the heads that are on there now. That LD4B intake is a good manifold correct? If I was to change the cam, would I have to change the springs etc.. on the heads? Thanks

Yes, If you change the cam, I'd get springs to match and a double roller timing chain. Your plan sounds good. LD4b is one of the best manifolds. I'd go with early magnum exhaust manifolds myself, they are cheap flow well and never leak, then get your dual exhaust.