check the slop in the control arms, Its taken me custom arms by Titan machine/ dieseldork on Cforum. A good stabilizer, I went thoren Trac Bar but BD is better. T style steering conversion from the stock Y style, one unit bearing, BD brace, ball joints, Bilstein 5100s, maxx links,Borgeson box, borgeson shaft(required with box) and quality e rated tires, allong with serious 5+ castor settings to acheive decent steering. also check the rear end alignment by measuring from the front spring stud to the center of each block.
Good luck and hope u have deep pockets.
My new pet peave is someone trying to buy the truck for trade in value, and u try and explain how you have poured thousands into it and they don't get it.