My New '69 Barracuda

15/16 is what I run, with a booster. Excellent feel. Very progressive, moderate force required. Not over assisted like most Mopes. You will need a proportioning valve; either one from a 73 type car which has a built in safety switch, or a stand alone adjustable one. This is to reduce rear pressure so they don't lock-up first., which they say induces the car to spin.
I found with 275 tires on the back and 235s up front, and 7/8 rear wheel cylinders, I did not need this item. I love my KHers and rear 10s