Put everything in then mate. I would have suggested that you fit the hot wire EFi anyway as the flapper fitted to the 3.5 isn't up to it.
BUT the system fitted to the P38 is a sequential system and more economical still.
You should be able to strip out the wiring loom for the system but it will need a couple of inputs "making up"
Probably the gearbox input for one, the road speed sensor for another. You can get round this by fitting the road speed sensor form a late RRC and the second speedo cable form a 1998 model, these few cars had hot wire EFi with the electronic speed signal and a mechanical speedo head, that's what you need.
IIRC you will also have coil packs so the engine will be less susceptible to water splashing (no dizzy).
Fitting an ealry V8 front end to the engine is possible if you wanted to keep it looking standard (flapper EFi and dizzy) but you need conversion parts, the flywheel you have needs to go, the P38 uses a 36-1 tooth wheel cast into the back face of the flywheel, to ensure it is fitted in the correct orientation one of the securing bolts is slightly out of place, so an early flywheel won't go on .
The exhausts are useless to you so look for a decent 4 branch system or at the very least a 3.9 or 4.2 EFi system, preferably ported.
Good luck :D
