1966 Dodge Dart

you need to check the pedal ratio, 4/5:1 for power brakes and about 6:1 for manual brakes. to check measure from pedal pivot to centre of foot pad, then pedal pivot to cylider pushrod attachment point/clevis. divide one by the other to get the ratio.
example pivot to pad 10", pivot to pushrod clevis 2" you have a 5:1 ratio.
manual brakes are just fine if the pedal ratio is right.
neil.