I used a Range Rover Classic LT77 with the 5th gear extension housing from a 200tdi defender LT77. This meant I could use the Defender Gear shift.
Speed Transducer - I didnt use one and its fine. Seems to vary though.
Fuel Pump - I used a range rover one, the smaller one actually fits straight into the defender tank, you just need to extend the pickup as the tank is deeper.
Engine mounts - we cut the defender one sout and welded in range rover ones.
Wiring, we used the Range Rover Engine and ECU loom and branched it into the Defender stuff. Stuck the ECU in the cubby box and ran the wiring up the tunnel.
Radiator - 2.5TD rad is huge and fills the whole front up.