KH disk front 83/4 rear, prop valve and master cylinder brake line question

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BTW the pedal pressure is probably more on the order of 200 lbs, not 500 lbs.... I know you were just using a number for comparison, but I doubt many owners could muscle up 500 lbs. even with both feet. I typically do 330lbs on the leg press at the gym, and even the 1-1/32 manual brakes aren't at that level.
the pounds of pressure in the system are amplified by the pedal linkage/ratio. It’s not 1 to 1..