How much does it cost and how hard is it to add power brakes to a 1965 mustang?
If you want power DISC brakes and the car is drum,You might get
lucky and find a disc equipped 'stang in a junkyard and get the parts,
or even the whole car for $500 or so...
If the car is a drum brake car, you can get a vacuum assist power drum setup by just adding the vacuum canister and a carburetor with
a power brake vacuum port. Those can be found in alot of older
Ford cars sitting around. Just bolt on and hook up a vacuum line.
$150 tops used. If you want all new parts,granted the cost will be
much more...Probably close to $600 to $1000 depending the type
of application. (disc or drum). Good Luck!