As long as you can adjust the shoes to take up the slack they may be wearing in and shaping themselves to the drums. If you are raising each wheel off the ground and adjusting them until they drag a little then driving I would keep at it until no more pedal loss. Are you sure the master cylinder is not bypassing fluid?

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy