i'm not sure what the front to back ratio is on a P4 gearbox as standard?
but, if you're aiming for a 200BHP target, which sound more than likely with a charger slapped in (Great!!) i think i'd probably be leaning towards keeping it 4wd, more for reason of reliability by sharing the torque rather than lumping it all to the back.
we all know that 200bhp is really quite pushing the boundaries of a stock Front 2wd 16v gearbox, and i believe its the casing that is often the failure, so, the torque that the gearbox will encounter from rear wheel drive snatching back in line etc, might just be too much i fear.
i would dearly love it to work as rwd, but i'd be concerned for your wallet Chris, and the best of luck with the whole thing anyway,
your garage stock is really taking shape this year eh mate?