I would go with billstein 5100's all around. Those self leveling kits guys are putting on top of their springs are causing some major damage when going wheeling. They find that things are snapping in two. Go w/the 5100's............you will be glad you did!
Get out your measuring tape and measure. I did this on a 0 mile truck at the dealership and it measured 35" front and 37.5" rear but after you drive and depending on how much weight and how often your haul your rear suspension will definately settle and in some cases sag. also because of the spring rate being as soft as it is in the rear you will notice small difference in ride height based on quantity of fuel and # of passengers. Trucks just dont ride at the same height all the time. If you want to keep it closer throw some timbrens in the back. Otherwise I would say that 1.5" is all you really need to level it once your rear susp is settled. Measure yours and that will tell you. ( i measured from the ground through the center of the wheel's center cap to the bottom edge of the fender. )