Manual to power brake swap

Sounds like you got original factory parts for your perhaps 1970's Duster or Demon. Note in post#2 the lever that is integral w/ the brackets. If missing, you will never figure it out. For others, there is a new setup w/ everything you need on ebay for <$140.

For factory setup, the critical parts are the brackets w/ lever and pedal rod. On my 1965 Dart, I put a booster/MC from a 95-99 Breeze on those brackets. Finding a good booster today is hard and a rebuilt one is $$ (see Booster Dewey), so I went with easier to source parts.