Bienvenu to the forums.
In your op you mentioned plans but didn't state you had the parts already. I was trying to save you some cash. ;-)
I'll admit that I have no real reason for rear disks, but if I found some for $100 local, my car would be sporting them within a couple weeks. So much sexier than drums.
Looking forward to some project pics.
Oh and if that car is from the rust belt, be prepared for some serious pita install work for anything g having to do with the undercarriage. Plan for twice the amount of time you think you need, and buy yourself a torch if you don't have one already. Heat is your new best friend.