Oh wow that's awesome! I do have questions! Haha I think I got most figured out but I'm curious what year the disk brake swap is and what all got swapped. That's so cool that you found it on here haha. Are you still in the area?
Scody's right. Front brakes/upper control arms were off a '73+ A-body from Pick-n-Pull. If I remember correctly, the 8-3/4 rearend was out of a b-body, so it's a tad wider than the A-body version. You know this, but it's all large bolt pattern stuff.