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So I just installed an 8” dual diaphragm booster into my 72. The reason for the swap was cause the factory setup is so ugly. I used captain fabs booster adapter to install it. After installation I bled the brakes, but my pedal felt low and spongy. I bled and re-bled the system with no change. I have read in the past that going from non-power to power brakes, that you needed to used the lower hole in the brake pedal. Well, I already had power brakes and there is not a second hole in my brake pedal. But the only thing I could think of that was causing my pedal to be low and my brakes spongy was pedal ratio. This issue was driving me crazy. Thinking about the factory setup, I realized it had a pivot in the bracket. I figured this is the change to the pedal ratio. When I got rid of it and out the rod to the same position in the brake pedal, it changed the ratio. So I measured and drilled a hole one inch lower in the brake pedal. My pedal instantly changed. It was firm and brake engagement was normal again. I’m posting this as I couldn’t find much info here on the forums. Hopefully this will help someone in the future.