those pics remind me of how much i hated my XR4i

speak to bernie about the gearbox mate, he sells RWD MT75s off the shelf (tis what ive got, but not made by bernie)

everyone else has provided the other relevant info, wiring aint as hard as youd think and 90% of it will bolt straight up. you miht have to raid a scrapyard for a few bits but nothing major, maybe a hose or something.