http://www.landyzone.co.uk/lz/f16/disco-2-engine-swap-see-what-i-did-211856.html
Completed a job like you're asking about almost 3 years ago.... The mechanics of swapping the engine and transmission is relatively easy. Sorting out the electrics so that your instrument panel works again is going to be a major head-scratcher.
All the best though, we always love a new project... that comes with loads of photos.