The front end geometry of the disco II is quite a bit better than the late Classics and Disco 1.
The early car was set up with very little positive caster, and any lift over about 2 1/2-3 inches would cause problems. Same problems occur on the P38.
But if you look at the front radius rods on the Disco II, you'll see that they cradle the front housing at a slightly greater angle. So unless you get stupid and decide to jack this thing way out the roof, you won't have to worry about it.
The kind of lift that Mike is talking about is just fine and won't cause you any grief. So unless you plan on making your Disco into the second coming of BigFoot. Don't sweat it!