Re: Body and suspention lift
You're dreaming if you think that the body only weighs 800lbs. I can get that with two doors, a box, and a core support. That's forgetting neat things like the tailgate, the front fenders, the hood, the inner wheelwells, and a 500+lb cab. This is skipping piddly-dink stuff like the radiator and all the [bleep] that hangs off the body under the hood (how about a 70lb battery, eh?). Unless you're some kind of goofball you're going to raise the 80+lb bumpers too so you might as well consider that part of the body.
Let's say the motor weighs 700lbs (we're talking a smallblock with all of its [bleep] hanging off it). NP208 and a 700R4 together probably weigh in the 400lb range (250 for the trans and 150 for the case). 500lbs for the raw frame (guessing since I cut up a 77C20 frame this summer), no neat stuff like fuel tanks which weigh ~40 without fuel in them.
If you start doing the math on the unsprung weight you will start to realize that a body lift doesn't benefit you that much as far as COM is concerned. Sure, there's a benefit, but not that much. Add the fact that you now have more frame flex (the twist from corner to opposite corner) the benefit becomes even smaller.
Start talking things like a K5 which has a very large and heavy body and a relatively small frame (shorter I should say) and it becomes even more obvious. You take the newer trucks which have even more bull**** hooked to the body, more weight in the cab, a wider but thinner frame and you really begin to realize how little weight is hooked to the frame.
All in all, a body lift is a cheap lift. It still raises things, well, the distance from the rockers to the asphalt gets larger. The frame and drivetrain is still down there up close and personal. The body mounts see a lot more stress. The frame sees more twisting and flexing. Sure, the difference between having a body lift and suspension lift will be noticeable in the corners, but not by much. The problem with a spring lift is that they can twist (the bigger the arch the more torque applied to the mounts) and you often get a rougher ride.