Yeah, I wouldn't go that far... you're parked on an incline. Put the truck on level ground and I bet your rear sits about 2 inches higher than the front.
It'll settle a bit, but not that much. Do you have balljoint spacers in? I'd do that, or if you already do maybe think about cutting 1 wrap off your helper coils in the rear.
Mine, with 12-inch, 125# springs after a few months:
Wheel rim to wheel well rim in front: 14"
Wheel rim to wheel well rim in rear: 12.5"
(People say rear in stock is 1.5" lower than front.)
Update on 22Mar2013: Frame to top of leaf pack now @ 9.25"
Not sure if OP cranked the torsion bar, but I'm happy. No rake.