Well, RPV(s) were standard on either a DUAL RESERVOIR DRUM-DRUM or DISC/DRUM (drum brake circuit) until about 1972 when FORD deleted the RPV and went to drum wheel cylinders using a cup expander design. As you can no longer buy original FORD (other than NOS) the aftermarkets may come through with or without. You have to know.
Same with a METERING VALVE as FORD changed MC calibration to negate them.
A 2# RPV on a DISC circuit is only used when the caliper is mounted below MC level.
The standard bore/piston size for a K-H design 4-piston caliper MC is 1 inch unless the car was/is a HP car.
The system has to have an adjustable PPV valve to control weight bias, especially in a panic stop situation. A METERING VALVE is suggested for proper performance and front pad longevity.
WILWOOD does not offer power assist so if wanted has to be sourced from another vendor.
1957 FORD DRUM/DRUM manual MC bore size was 1" while power assist was 1 1/8"
You have to cipher exactly what it is you are trying to do and plan/buy from there.
Using GM style braking system(s) is a completely different story.
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