Issues Bleeding 70 dart with Kelsey Hayes brakes

Depending on your tire sizes and rear wheel cylinder sizes. you may not need any proportioning at all.
With 235s up front and 275s in the back, I swapped to 7/8" w/cs in the 10" rear drums, and use no proportioning at all. Works great. With 295s I'm sure I could go back to 15/16.And I would try it if I wasn't so lazy, nowadays. Best stopping car I've ever had.