68 Dart GTS brake problems

After sitting on jack stands for 25 years I replaced the entire drum power brake system front to back with the exception of the PB Booster and wheel drums. Everything is all stock. I used DOT 5 fluid and had a problem sealing it up. I wound up using copper gaskets on some most of the fittings which finally stopped the leaks. The brakes finally work but they're not right.

The brakes are a little mushy and when stopping the pedal goes pretty low to the floor. After applying them if I pump the pedal it comes up high and gets real hard but does not translate to more braking power and actually a little less.

I've tried standing on the brakes to see if I could lock them up but they won't.

Any ideas?

Thanks