Swap in rear discs 70 Dart
I have a 70 Dart with 73+ discs up front and Dr. Diff rear discs. Here's what you need:
Caliper kit and rotors (You need to call him m for SBP brackets)
15/16 Master cylinder
4 bolt to 2 bolt adapter for master
Stock DISTRIBUTION valve (replaces the proportion valve.)
Manual brake rod works fine. Your rear line will have to be cut and flared. I took my line down to a local brake shop and they flared for like $6.
All of that and your set.