Disk brake help

Those would not be the original brakes. A 1971 with disks would have the 4-piston Kelsey-Hays calipers, and your slant six car would probably have had drums. Those look like the 73-up brakes, and I'm pretty sure they are large bolt pattern.

Since they seem to be mounted toward the front of the wheel, normal A-body sway bars probably won't fit. The 73-up A-bodies had a different sway bar design and a different K-frame. This is the problem you get with swapping parts. You can reverse these to mount toward the rear by switching side to side. Then a 67-72 sway bar would fit. I like the Hellwig hollow bar.