A liner generally won't drop by much. On mine it would only have dopped about 0.25mm, the only way to tell is to put a straight edge across the block with the heads removed.
Theoretically if the motors had been built properly and every liner pushed home onto the block then yes, you possibly could tell, but then again if that was the case they wouldn't move anyway. The problem occurs that in the factory landrover did not push all the liners all the way in and then machined the deck making all the liners level at the top, but not level at the bottom. Hence when the block cracks it loses its hold and the liner moves down to the bottom. Once this occurs it just gets worse and worse.