Be careful with too much air in the air shocks, they have been know to rip the upper shock mounts out.
i was just watching Gears with Stacey David, and he said when cutting springs to take a half coil to start with and go from there..it was like a sign from god to cut my front springs a 1/2 coil..lol
Well....you don't have to call me THAT. Let the air out of you shocks. Cut a half coil off the front. You might find you will not need to lower the rear at all.