There are no readily availabe EFI intakes for the Stage Two Buick V6 heads. There are, however, loads of beautifully ported, cheap 4 bbl intakes left over from circle track race cars. I paid $50 for this manifold and about $200 for the fuel rail, bungs, and "elbow" necessary to convert it to EFI.

You can get the bungs & rail stock from PT&E, Kinsler, and others; mine came from PT&E. I visually aligned the bungs to the center of the ports, then scribed the parallel line to locate the plane that lines them up. I drilled the holes in a drill press, using a bit sized so that the bungs just slipped in. I did mine vertically; if you want to lean them over in either plane to target the ports better you'll require some sort of jig to align everything.

I scratched my head for a while wondering how to hold the bungs for welding..I ended up marking the fuel rail, drilling it for the injectors, and inserting scrap injectors into the rail and bungs. I then clamped this whole mess down and proceeded to weld the bungs. Even with this method, I ended up with a couple that were slightly off and since I had access to a mill, I milled the tops to even them up.

Since I did mine, I saw somebody else's site where they cut pieces of wooden dowel sized to press into the bungs, then made a wooden rail on both sides and cross pieces that bolted to the carb flange. I like that idea and it'd probably work better with less fuss.

After you've got the bungs in and the rail drilled, you need to fabricate rail hold downs; I made 2 small diagonals per side that are tapped for a bolt through the bottom of the rail and welded them to the front and rear runner.

For a throttle body, you have several options: since this is for a twin turbo S2 V6 so I went with an elbow PT&E sells that allows mounting a 90mm Ford TB. This is convenient for me since it's round and aimed toward the front. You can buy a 4 bbl throttle body. The cheapest thing would be to use a 4 bbl carb baseplate, and put a carb spacer on top of it for a smooth entrance to the baseplate. I saw this in a lowbuck EFI article in some (gasp) Mopar mag.