What is this?

junkyardhero said
not to say that ford stuff doesn't work, but given the state of affairs i wouldn't even bother attempting to rebuild it. besides the fact that it's off of an unknown application so who knows what the porportioning is on that.

you'd be much better off with something like this:

[URL][URL]https://www.ebay.com/itm/...mbRecallManual&_trksid=p2332490.c101875.m1851[/URL][/URL]

Also depends on what the rest of the system is composed of- so many aftermarket conversion kits use Ford or Chevy master cylinders (or Wilwood) that it's hard to believe that any factory prop valve would have correct proportioning built in.
"Mopar" kit with Chevy master:

"Mopar" kit with Ford master:

Not that these kits can't be made to work, but it can take a bit of finagling to do it. If this is what the OP is dealing with, best bet would be to plumb the front brake circuit directly into the rear master reservoir, and the front reservoir directly into an adjustable prop valve to the rear brakes; and skip any sort of factory prop valve.
A Mopar prop valve is best used in conjunction with a Mopar Master and brakes, and if that's not what you have then just go with an adjustable unit. It would probably be cheaper than a repro Mopar unit, too.

A picture of the OP's system would help a lot.