I didnt know the intake flip was possible, what all did it take? I have a buddy running a 6.0L for mud racing and this may be a big help to him.
Kiel's buggy build thread has some detailed info if you want to check it out, but it wasn't bad. He and I are both running LS1 intakes, but it should be even easier if your friend uses the truck manifold. The bolt pattern is symetrical, so actually rotating the intake is easy.
Really, the hardest part was coming up with a way to mount the truck injectors in the car manifold. Earlier in this thread I posted pics showing how I enlarged a portion of the injector bore, but I think this could be avoided by removing the plasic "nose" from the truck injectors. I had to fab up some brackets so that truck fuel rails would bolt to the LS1 intake (the truck injectors won't fit in the car fuel rails). The brackets are pretty simple, but If you'd like pics let me know.
I still have to extend the MAP sensor wiring.
My engine is drive by wire, so I didn't have to revamp anything with the throttle cable.