Techie question ... (Jeep)

[rob love]

Do you have some amount of freeplay on the pedal? If you push the pedal with your fingers, there shoudl be a half inch or so before the pushrod actually contacts the piston.
As to overfilling, there is normally a vent on top of the master cylinder, so it should not be retaining any pressure in the reservoir, unless you have blocked off the vent. Without the vent, the heating of the cylinder from the nearby exhaust pipe can result in reservoir pressure and dragging brakes.