brakes

I have an '84 mazda 626 and I just changed the master cylinder. I bled the master and all 4 wheels and still don't have much pedal. The pedal goes to the floor but will hold the car on a hill. The front brakes have more than half the pads and the back shoes are pretty much gone, and the brake fluid is really dark. I expected more pedal than that despite what needs to be done. If I do the back brakes and flush the brake fluid I should have a full pedal right?

Rear drum brakes only do about 25% of the braking but if there out of adjustemnt it will give you a lower than normal brake pedal.