Indeed, its the V6 particually that appeals, much smoother than a straight 5 like my current TD5.
I would think keeping the gearbox (be it auto or manual) could be the best way, and mate that to the t-box (LT230) to keep the props and hi/lo range already in the setup.
As far as torsen diffs, the true-trac LSD is a torsen torque biasing diff and works very well, both on and off road.
The conversion is somthing i am considering, obviously cost and time to do it are bog factors, as are getting over fitting and mating defender to audi type problems.