73 duster drum in rear disk up front manual brakes. any thoughts on common upgrades to improve braking. Car does stop ok with heavy foot pedal. Not sure how safe in a panic stop though.
If you cannot stop (lock up) an A body with front disks, there is something wrong "with what's there." Either you have the wrong size master, wrong size wheel cylinders, or the lining is badly glazed, and or the drums are not matched to the shoes. No you do not need a booster.
FIRST thing I'd do is inspect everything, front to rear. Condition of pads. If you cannot identify what/ where from they came, replace them with something of known quality. Break in the pads. Inspect the rears for adjustment and shoe fit in the drums. Read your shop manual. Determine the master bore size and make sure it is NO LARGER than factory. Smaller gives you more braking pressure
"Most likely" is glazed lining and pads and cheap lining and pads, assuming you have a nice hard pedal
My legs are not very strong, I have arthritic related problems. I cannot walk very far. I could lock mine up EASY at 35--40 and locked them up "briefly" just testing at 65. It did take some "foot pressure"