You can fit anything (within reason)with a suitable amount of imagination, the right skills and a lot of swearing.
I have a 2.0 TC in my shed eventually waiting for a home in a Cinq - it'd pretty much fill the engine bay without ancilliaries, so it's not going here.
Back seats are coming out, a damn big hole is being cut and its going in there.
N2O systems are difficult to manage correctly - same with a turbo / supercharger installation. YOu'll be breaking manifold welds, and dropping floorpans without a doubt!