Yup, whether you lift the body only or the entire chassis, you're still raising the center of gravity, and that does affect handling. A body lift will have slightly less effect than a suspension lift though, since the frame and driveline are still at the lower height.
Oh another note, I HIGHLY recommend you NOT put a 3" body lift under your truck.
First, it'll leave the frame hanging obviously low on a truck where the frame is already low. You're not likely to get hung up because the front or rear bumper are dragging, it's the middle of the truck and breakover angle that usually get in the way of forward progress. If you have a receiver hitch, it will also still hang just as low as it does now, which really makes it moot to raise the bumper.
Second, lifting the body that far will require modifications to quite a bit of stuff, and put a good bit of stress into things that may not appreciate it. (Coolant hoses, wiring harnesses, fuel filler, steering shaft, A/C lines...)
Third, the bumper brackets that are used with body lifts are fairly hokey... Yes, they move the bumpers up, but a fairly significant loss of structural integrity to them.
Lastly, unless you want to run 35's, a 3" body lift is way more than you need for just going up a few tire sizes.
Not sure what size tire you'd like to run, but a 265/75R16 should easily fit your truck with no lift. If you'd like something more like a 33" tire, you can easily adjust the front up an inch or so with the torsion bar bolts. Then 285's should fit just as well. If your truck sits pretty level already, you can turn the front up 1" and then add a 1" or 1-1/2" block to the back. That'll get the frame and bumpers up without making the truck look silly with the frame hanging down below the body.
No, "cranking" up the bars won't make it ride like crap unless you crank it up a lot. Adjusting the bolts does EXACTLY the same thing as a "leveling kit" with new keys, and the keys are a real pain to install. For 1" or so of ride height increase, you won't notice a difference, or the ride will get
vehicletreat better if you're sitting on the jounce bumpers in the front now. If you want to go more than 1" or so, I'd get longer front shocks, or space up the shock brackets 1/2" or so off the lower control arm so you still have a decent amount of droop travel.
If you really want it to be a little taller after that, then you could do a small body lift too. The zone has a 1-1/2" kit. If you can find a 1" kit, that might be a better option. But I really recommend keeping the body lift low if done at all.
Just my $.05. (Probably worth less than $.02 after inflation...)
