47-55.1 Brake Pedal Travel?

[MiraclePieCo]

7" POL dual chamber power booster, Mustang II front discs, GM rear drums.

With the engine off I have just 1 inch of pedal travel. With the engine running I have about 3 inches - about half way to the floor. This seems like excessive pedal travel - is it? I have bled the MC, bled all four brakes, adjusted the rear drum brakes, and adjusted my booster pushrod. Brakes work great, had to lock 'em up recently when a deer jumped out in front of me. Since there's a big difference in running/not running pedal travel I suspect the issue lies in the booster? I did lengthen the pedal arm a couple of inches, but I wouldn't think that would account for that much difference. What am I missing here?