I've heard that too about the differences. I've built 383s before and been happy. A good machine shop should be able to accomplish what you want. I'm a fan of letting the machine shop order your parts too so that it all comes together well. Any mistakes and it's on the builder. They can do lots of things to get the compression where you want it but a little bit lower like 9:1 is not necessarily bad. The key is using a cam that's designed to work with the compression ratio. My knowledge of cam selection is so basic that again, I allow my machine shop buddy to help me make the right selections for what I want. I just tell him how much power I want, where in the power band I want it, what sort of idle speed and quality I want, how much vacuum at idle I need, etc and he has never let me down.
Too bad you're not on the west coast...I have a nice 400 taking up space. The guy I picked it up from already milled the heads and intake to bring the compression back up to a decent level since the 400s were notoriously low.