v8 classic to diesel,manweel gearbox question

hello all, i have a 85 v8 manual range rover classic.
i am going to fit a 300 tdi oil burner to her,i know the disco engine and box will go straight in and all il have to is alter the center consol as the gear stick will come up a bit further back, (i have a whole 95` 300 manual disco i am going to break up). the gearbox that is in the disco is a bit dodgy in second gear, feels like a very worn syncro hub as it dosnt catch 2nd all the time, so i have to either repair it or get another box. what would i have to do to make the v8 box fit, then i could leave the center consol as it is. mines a 5 speed box with long gear stick.
any one done this or have any ideas
regards David T

get a diesel lt77 or r380 box out of a disco.defender ones geared to low.

thanks for the advice B O B, didnt know defender box was geared low as that was one of my ideas. what would i have to do to marry up my v8 box to the tdi, oviously swap bellhousings, would the input shaft be to long?