Edelbrock makes a vortech manifold like the Marine manifold as shown I just don't know where you would buy the throttle body adapter.
http://www.summitracing.com/parts/EDL-29135/

Either he never started the project or something happened. I hate it when they don't finish threads.

This is the CARB version. No injector bosses.

Intersting, but the operating RPM of it is only 3500-8000. A very tad high for my range. Mine is usually 1000 to 3000 LOL.

Marine intake upgrade Vortec 350....BUT....not your normal marine intake! - *-10 Forum

click that first one, its the oem mercruiser design, it has standard mpfi injectors

the second one would be if you wanted to do a blow through carb, but not real appropriate for a 96+ in our state. i would do this if you where doing a retrofit to a pre 96 vehicle and wanted to do a carb setup

I found this and it has better pictures of the marine set up.
GM Performance :: View topic - Vortec L31 MARINE MANIFOLD project! Q&A

I've seen these marine intakes being installed on the 4.3'* and they say its a bear because of some modifications that have to be made.

the only difference i can think of is using an external regulator and adapting what ever thread that may be to the stock rail and the line coming up from the pump. you already have a good enough pump and proper pressure there. you would have to take the wires from the plug on top and run them to their respective cylinders, that would require soldering in a little extension wire. after that its just tuning which you already have the software