the crossmembers are the same for all the 1/2, 3/4, and 1 ton trucks as long as they are 2 wheel drive. the arms all mount the same but have small differences.
the later (73-87) arms will fit trucks back to 63.
you can section (cut 1.5") off the bottom of the frame and Z the front 2.5" and lay cab without doing a body drop.
plus Energy Suspension also make aftermarket polyurethane body mounts that are about an inch shorter than the height of the stock mounts.
theres several ways of doing this. its just a matter of doing some research as to the best way for your particular setup.
the wheel and tire size is also a factor as to which is best for your ride.
http://www.builtbybyc.com/86chevy