"Fade" is caused by overheating, period. The symptoms are a very firm pedal, and no stopping effect. If the shoes are putting heat into the drums faster than the airflow around them can dissipate it, there is plenty of pedal, and no stop. That's usually caused by heavy loads, and/or long downgrades at too high a speed.
If the pedal is getting lower as you drive, there's either air in the system you haven't bled out, or air is leaking past the M/C piston as the brakes are used repeatedly. I'd suggest rebuilding or replacing the master cylinder, and a full flush and bleed to replace any moisture-contaminated brake fluid. You can go as high up the chain as DOT 4 fluid, but don't use DOT 5 unless you're willing to rebuild the whole system, wheel cylinders and all. DOT 5 is silicone-based, and isn't compatible with lower grades of fluid.
Jerry
