A set of used Jeep Wagoneer springs(44044) IIRC, will lift the front and offer a nice ride with plenty of flex. A set of 1/2ton chevy's in the rear with a new main leaf cut to the desired 4" of lift will finish the rear. Depending on labor for your area, the new longer rear mains should run about $100/pair, the chevy springs $50-125/pair, and about the same for the used Wagoneer springs. This is the set-up on this '85(minus the lift spring, 3" blocks were used in the rear). The truck had plenty of flex and nice ride for an SA rig. [Linked Image]

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed