no need to change the rear end at all, just leave the 2wd axle on complete
and the clutch is the same, just the release bearing thats differant(as already mentioned above)
the 2wd and 4x4 diff ratio's are very slightly differant, but they are within tolerance to be used either way around
its been done 100's if not 1000's of times with no prob so defo works with no future probs to worry about
in fact it used to be quite common to convert a 4x4 to a rwd axle as the larger 7.5 inch diff was stronger than the 7inch 4x4 diff