3.9 v8 and auto box in a defender td5

Hi I’m just about to buy a 300 series discovery as a donor car to rob the 3.9 efi and auto box to put in my td5 90.
Has anyone done this and can offer any tips or info???
Does the gearbox fit in terms of length and space in the chassis?
Propshaft adjustments??
And tips on how to mate up the speedo etc.
I will have the entire working disco to donor from.
Any useful advice would be great.
I love the TD5 but I love the V8 and auto more!!! And a 90 v8 auto is my dream car.

Not done this particular conversion. Which Lt230 are you planning on using?

Personally I'd keep the R380. The auto kills the fun, performance and mpg of a V8 IMO.