The EA82 rear rotors would be too small in diameter I think. Hmm... Thinking. You should be able to make rear caliper mounts from some flat steel stock. I have a complete EA82 rear disc set up off the car right now (not for sale, sorry). I can send along pictures and measurements of that too if it helps. You might just have to fab up something. We can help!
Here are some EA82 Turbo Wagon rear disc backing plates that I pulled at the local P-N-P and cleaned up for a project a couple years back. You only really need the thick center portion to mount the caliper. The rest just keeps the rotor cool and sheds debris or water. As you can see from the pictures above, any cut up old drum backing plate works as a drill-hole template for making what you need.
EA82 Rear plate - 1.jpg 77.31K
EA82 Rear plate - 2.jpg 78.92K
Edited by Crazyeights, 13 May 2014 - 08:49 AM.