The alignnment rings aren't just a good idea, they're absolutely essential for a good, leak-free assembly. Ditto on the milling of the manifolds, especially the exhaust. I don't believe both manifolds can be milled as an assembly, however. One word of advice, tighten the intake/exhaust flange, where the heat riser fits, after all the manifold-to-head bolts & nuts are torqued. This allows both manifolds to get the best possible fit to the head, before they're pulled together.
Jerry
