So I got into the brakes in the front left.
The wheel cylinder was a little nasty to say the least. I didn't have a rebuild kit, so I figured it would be good enough to clean it out. Got it all put back together and bled the whole system. The brakes work much better and don't fade to the floor when stopped.

But a couple of questions:
1. When should the brakes engage and start stopping? The really don't do that until the pedal is about 8" from the floor.
2. It now pulls to the right when braking. That's odd, considering it didn't do that before and the left front wasn't getting any fluid. Do I maybe need to adjust the shoes?

Here are some pics for your enjoyment:
http://captaincheeto.com/pictures/64-gmc/brakes/index.html

There is one place that you have not looked, and it is there - only there - that you shall find the master.