drum brake proportioning valve
Ok if the master is correct then start by pulling the drums one by one and use a screwdriver on the front and one on the rear shoe. When someone pushes on the pedal it should push the front and rear shoe out if the wheel cylinders are not frozen. If not replace them. The next step is to be sure you dont have the primary and secondary shoes in the wrong spot. This will cause more pressure and distance to stop if it is wrong. The long lining should be on the rear and the short on the front. After we are sure you have this correct we can check further. I have been ASE certified and worked as a licensed mechanic for 28 years so if the master is right these are your next steps.