I'm going to a flat bed, with some rear seats as soon as I can find the time and the motivation to do so.
The spring pack gets too tall, so the parking brake drags across it. It's not clear in the photo, but you need to extend the arm that is on the drum brake. I simply welded on to it and drilled a hole for the pin. I believe that someone actually makes an extension.
What you need to understand about doing ANY lift:
1) If you lift, you just changed your pinion angle. The rule that I've heard is for every inch up, you need to rotate the pinion by 1.5 degrees. The rear isn't as bad because the angles are not as extreme. A bad pinion angle in back will result in u-joints that wear more quickly and inefficient power transfer.. Not a big deal.
2) The front is more problematic because you can end up with a very bad (unusable) pinion angle. If you shim the front - you'll screw up your default caster, which is what keeps your truck stable on the road. Not enough caster and you'll "death wobble" - the truck will be highly unstable, not drivable, and dangerous on the road... To do the SAS right, you need to cut and rotate the ends of the axle (see pirate4x4) - to get your pinion angle correct.. you'll need to reweld the spring perches also. It's a pain...
I'd recommend not shimming the front - that way your pinion angle might be bad, but you're not going to death wobble. Jess (high angle driveline) can produce some driveshafts that work well, but they will vibrate quite a bit and not be smooth above about 20mph...
email me if you've got questions. firstname.lastname@example.org