Oddball car - swap to disc - ideas?

Since you should already have the large ball joint control arms just go with the A, F, M, J spindle swap. Cars like the 85 5th Avenue should be fairly common in the salvage yards....

How do I know I have the large ball joint.
If this is what I have, then all I need from the salvage yard, is the spindles, caliper brackets? What rotors do I use? I appreciate the help.