Brent,
 The brake fade you are experiencing is due to vaporization of brake fluid (more
specifically, whatever is in your brake lines, it may be a combination of brake
fluid and H2O). What kind of fluid did you use? What is its boiling point? You
mentioned the need to pump once to gain a firm pedal, that is a sign of air
in the brake hydraulic system, how did you bleed the brakes? Did you flush the
lines until clear? When towards the end of bleeding, I always open the bleeders
a minimal amount to keep air from being sucked back past the threads of the
bleeder. You can identify the amount of bleeder opening which allows air to
be sucked past the threads by observing the amount of bleeder opening which
causes more bubbles in the bleed stream (due to a venturi type effect). Also
make sure you close the bleeder before positive pressure is lost.
   Can you spin the wheels freely or are the calipers binding? Perhaps if air
is in the system, it is staying slightly pressurized after letting off the brake
pedal causing brake system heating during normal driving. Did you adjust the
rear shoes properly so as not to bind? When driving long mountain passes, I
always use the engine to brake as much as possible (difficult on our Auto Westy,
but still possible).
  You can help minimize reduction in braking due to gassing at the pad/rotor
interface by slotting your brake pads. Do this by using two hack saw blades
in parallel to score a groove (approx 1/4" deep) in the center of each pad parallel
with a radia drawn from the center of the rotor (short direction of the pad).
This slot will help gasses escape the pad/rotor interface.
  Use a high quality brake fluid. Castrol GT LMA is ok, if you are still experiencing
problems you could move to a higher temp fluid, but make sure you flush it more
often as higher temp/performance brake fluids also absorb moisture at a faster
rate.
Good Luck, be safe!
Ezra
'88 Westy, 94K
'86 944, 260K