Dr. Diff sells a kit with a caliper adapter that is made for your spindles and Wilwood calipers. He sells a complete kit (which you don't need) on his website. He also sells just the adapters, hardware and hoses on eBay. You would need to source the calipers. It only works with the 11.75" rotors, and at least 15" wheels, so if you have the 10.87" rotors, you'd need to get the bigger ones. He also says that the calipers have to be mounted to the rear on A-bodies. Do this by swapping spindles to the opposite sides.
Give him a call, and see if he won't sell you just want you need.
Maybe it's just me, but I'd be changing those lower control arms.
