LS is easy to do with the transplant kits available. Turbo is going to be a different proposition. If you are thinking of a high horse high boost motor it goes without saying to build a motor just for the level of boost you are planning on building. The key word is planning.
I saw a blurb on the California Emissions Board in passing (just caught the headline didn't read the article) about requiring Cats and AIR pumps and all of the rest of the silliness found on a modern LS-x motor even if it is being put into a "tin lizzy". Don't know how that will affect you as there are about seven other states that Monkey see Monkey do to rubber stamp anything CA does.