[jbclassix]

after reading your post twice I think what you are looking for is body height off the ground? If you are here some points...

body height effects powertrain clearance
body height determines how the truck looks overall
body height effects center of gravity

If you have the engine/tranny I would get them on the frame.
get a set of wheels on (pref the height of the tire you want to run).
mount your front fenders on your cab
set your cab over your frame
center your front wheels in the fenders
set your bed over the frame
use the denali screw jacks to pos the body where it looks good to YOU...
since you are not using a stock frame and building your own custom body mounts the choice is yours. this will also give you a good point to determine your rear axle CL in the wheel wells. Did i ramble or am i way off?