I think Rich meant, you cant fit the 350z engine combined with the 350z ecu and expect it to work, not the engine doesnt fit. If you cant find a solution to access to the ecu, pretty pointless fitting forced induction.
Sure its feasable with the right 350 specialist, but, being the first do it, will require some hefty r and costs.
I would imagine the detune is probably down to something very simple like cams, i guess the theory will be you wont be using a vans power at 7000 rpm.