Let us know how you're getting on, malcs90. I did the same thing with my 90 and its great.
The wiring is pretty straightforward, The EFI loom comes out of the rangie a piece of cake, there is a multiplug next to your left ankle (when sat in drivers seat) that needs disconecting, and the ECU (under drivers seat). Then all the wiring you need will pull through the bulkhead from the engine side through a hole just big enough for the ECU plug. Measure this hole, as landrover used 2 different sizes, and drill the same size in you 90 so you can use that nice big rubber grommet again. I managed to get mine through next to the fuse box (and covered it with the plastic fusebox cover) then ran the wiring along the tunnel under the carpet and mounted the ECU up between the seats, out of harms way (water).
At the white multiplug, the big fat brown and orange cable needs a permanent live from battery, no need to fuse it as it is fused at the ECU end of the loom, once for ign, and again for fuel pump. The 2 relays there are IGN (black base) and fuel pump (blue base) The white wire with a grey stripe needs an ign live ,from key, and the purple and white wire is the positive feed for your fuel pump. The only other essential wiring is a -ve input from coil, mark this on disassembly. As you're taking out a diesel, use the wire to the stop solenoid on the diesel pump as your coil +ve. Mark up the oil pressure switch wire, temp sender wire and alternator connections as you remove them from the diesel, you may need to extend /shorten these as neccessary.
I didn't bother with the speed transducer input for the ECU, and although this may mean that I am only running on an 'idle' fuel map, it still kicks arse.
The props I used are both the same, and are Rangerover v8 auto front props.
Didn't realise how long I had been ranting on, but hope this helps. shout up if there's owt I can help with, Dave.