71 demon brake questions.

If the light is good, it should come on. Never let the pedal go to the floor.
Try this; go to the back, just barely crack the bleeder- no air? do the same to the other side.

Now go to the front, barely crack a bleeder and push; you might feel a click in the pedal, and or the light goes off. Don't push further until the bleeder is closed, If that worked, the valve is now re-centered.

Re-bleed, only push the pedal half way down.