Dude, 3" of body lift and longer shackles is not the proper way to lift. Consider getting away from both and installing some quality lift springs and you'll have fewer problems in the long run. Your jeep will be safer and perform better.
I wouldn't go over 1" in BL and no more than a 1" longer shackle. Any more and you put a lot of stress on the body mounts/bolts, and you mess with pinion angles and caster.