Matt,
Everything you said is correct, but if you use a pre 1966 engine, there is no smog to pass as they never started having the smog tests until 66. And even then, any well tuned engine should pass as they weren't so strict as now. I have had two 1965s, one a 390 and the Comet with the 289. Only smog equipment was a PCV valve and they are not required to be checked ever for smog as there are no standards for 65 and back. The main problem around here with using a newer engine is finding the junk they hung on them for smog. So if I were doing it by engine year, I would get a 1965 or earlier block.
Ron
