hard brake pedal

Ok guys, this question is actually on a 67 newport custom, not my duster, but the principle is the same, so here goes.

I just converted my 67 newport custom to front disc brakes, using all factory original parts, and spindles off a 73 newport. Brakes bled fine, as I installed a disc master and power booster when I did the swap. Before it was power drums on front. Now, my pedal is hard as a rock and wont even depress enough to activate the brake lights. Is there a possibility that the new booster is junk. When the car is idling, I can hear air rushing down around the brake pedal inside the car. Everything bolted up nicely, didnt have to modify anything, and when I bled the brakes the pedal went all the way to the floor. However, now, like I said, whether the car is running or not, the pedal is rock hard. Also, I verified good vacuum to the booster and out of the check valve in the booster. I'm leaning towards bad/leaking brand new booster, but anyone else have any other possibilities? The booster is a dual diaphragm design, should I have went with single diaphragm, or does that not matter?