I am changing to manual disc brakes on my comet.My question is will I need an adapter on the fire wall to install the dual master brake cyl ? or will the master cyl just bolt in place of the power booster? thank you.
You shouldn't need an adapter. A dual well '67 Mustang master bolts right in place on a '65/'66 Mustang. Can't see a Comet being much different. Make sure you get a manual disc/drum master from a similar size/weight car for your update, like Mustang /Cougar.