diesel engine in a 1982 Range Rover Classic

I've got a 3.636l Isuzu diesel engine, I plan to put into a Range Rover, I was wondering if anyone else on the forum has done a similar conversion.
I was going to make an adapter myself to couple the engine to the 4 speed Range Rover gearbox, but I was thinking maybe I should get a later model transfer case, which is separate from the gearbox and use the 5 speed Isuzu gearbox, which would require a simple adapter from the Isuzu box to the transfer case.
Any input from members of this forum would be appreciated.
Kind regards...Ron.

Think I'd stick to the 4spd box with a bigger 4cyl diesel like that.Isnt the bellhousing the same as your 3.9 Isuzu ? Are the Oz army still thrashing round those 110's and 6wd ones out there - any ex army spares available to help you ?