I'm doing similar buddy with a 2wd. As a rough budget I'd say :
Engine £1500, Gearbox £350, L6 ECU £150, Suspension set up £350, Brakes £500 incl calipers. Just a rough idea though mind you. You have to remember all the 'little bits' though, cos that's where the money goes. All the gaskets, nuts, bolts, hoses, brackets, postage/collection costs, fluids, service items, sensors etc etc.
And if you're gonna do it, do it properly or not at all I say!
So no rusty nuts/bolts, re-using gaskets etc.


Good luck with it buddy

cheeRS