you have a lot of options regarding brake upgrades, and you dont need to change out the power booster you now have, but you will need the change the master cylinder. your front brake options start with scarebird mechanical for just the brackets, all the way up to complete kits from a number of suppliers. you first have to decide what level of braking power you want, and go from there. if this is a daily driver, go with either the factory style disc brakes that ford used on the 65-67 mustangs, or if your local parts availability is more limited, go with something like the scarebird or rod and custom brake kits. scarebird and R&C use later model parts that are more readily available, but you will have to deal with using gm style parts on your ford.
if you are willing to step up to 17" wheels, then mustang steve and vintage venom have the brackets for you. these kits use late model cobra rotors and calipers, and the brackets bolt to your stock spindles.
one other option is to find a granada/monarch or maverick with disc brakes and grab the spindles, rotors, calipers, caliper brackets, and use those to put disc brakes on your car. this option however requires you to replace the spindles, and since you do that you will need to at least check the alignment when you are done with the brake conversion.
