Diesel conversion options for 86 RRC 4 speed auto

[MJH]

I want to set up my old RRC for long range touring of the Australian outback as i have just done a 5600km trip to Cape York and back in a std 3.5 ltr V8 on dual fuel and had plenty of unleaded fuel available but struggled with range even with Jerry cans.
The other problem was wading depth and the ECU under the front seat.
I love the 4 sp auto for off roading as I left and right foot and always have the handbrake well adjusted for the down hill stuff.
I am interested in anyone who has converted a V8 to diesel using the ZF box.
What are the good options as I have a TDI 300 in my Disco that handles itself very well and is not over the top electronically.
We did get some RRC with the 200TDI in them but they are very rare.
Any thoughts and advice would be very welcomed.
Many Thanks.
Mike.