I got some free time today to work on the truck.
So, I jacked it up and removed the rear axle, springs, and trailing arms. Then, I put in another set of trailing arms with fresh bushings, a 5 lug rear axle, and new lowering springs. Now, the truck is updated to good brakes and 5 lug wheels on all 4 corners. There are still some details to attend to under there, namely building all new brake lines, hooking up the park brake cables and installing the shock absorbers. But, the heavy hard stuff is done now.
This truck is going to drive soon if it kills me.