well, if it is an auto, yer might or might not have fooked the gearbox.
anyway, if it's a V6, the engine needs to come out to do the rear bank.
use the upgraded MLS gasket, get the heads skimmed and fit a new oil rail.
special tools are needed for re-timing it.
many garages won't do it because of a high probability of it failing again - they don't want to guarantee their work.
a LR main dealer will tell you that it needs a new engine - about 4 grand.
if yer do fix it - sell it quick!