I would recommend not using the 76 up calipers. I did this, and due to the larger bore, I had to change from a 15/16 MC to a 1 1/32 bore MC. The 15/16 did not move enough volume to operate the larger calipers.
Not sure what your particular brake issue was, but I use a 15/16" master with the larger 2.75" bore calipers. They work great. Keep in mind that all of the B/E body pin type calipers had a piston bore of 2.75". I just converted my Challenger over to manual brakes with a Dr. Diff 15/16" master cylinder and had no issues with the pedal.