It's good to have good shocks, so you can't really count that toward the cost. I'd go with Rancho 9000s and turn them all of the way up in the rear with TC loaded.
I'd consider adding a larger sway bar. I'm unsure if those came with sway bars or not. That's about $500.
I'd add 19.5s. If those are the original tires, they would need replacing due to age, so that's part of the cost of buying tires. New 19.5s wheels/tires are 2500-4000. Then, I'd add stableloads if they are made for his truck. That's about 300.
It's possible he can find used 19.5s, but otherwise with labor he's looking at 3000-4000K realistically. Those changes will make a huge difference.
