If I were to do all that work I would get a 3.8 out of a 97 or something. They make performance heads, cams, headers, everything for that motor. It would probably be worth it in the end to do that. Also, you think an LS1 swap is harder than a half 3.4 half 3.5 turbo motor build up? It will probably be even if not way harder due to all of the custom work involved. It would be a lot of work and money for the LS1 but at least you can buy the harness, motor, fuel system, etc and have it all fit fine. Not to mention those engine bays are such a pain to work in!
Not putting down your idea, that would be a very cool build. Just wouldn't want you to get halfway in and realize you should have gone a different route. If thats what you want to do I look forward to watching the build and good luck