Sorry for digging up an old thread, but I wanted to offer this suggestion:
Use the Durango R/T self leveling shocks. Same platform as Grand Cherokee, but lowered about an inch. The R/T self leveling shocks are shorter to accommodate this. It might give you another 1/2 inch of lowering versus using the GC self leveling shocks, and you get to keep the feature.
I'm hoping to pick up a Used GC or Durango soon myself.