The brakes do release when the pedal is let up, and I don't think there is any major dragging.

I'm wondering if there isn't a problem with the booster rod being too long, since I assume there is some adjustment that can be made there. I'll see what I can find for a FSM online since I left mine at the shop. The other thing I can do is measure the length of the old rod from the drum booster assembly since that is in the back of my Armada.

I just found this nugget on the Online Imperial Club's site;
Question from Don (1968):

My problem is the front brakes don't release-I don't know what the rear brakes are doing but definitely the fronts won't release. Today I parked the car in my driveway which has a substantial slant to it. I put the car in NEUTRAL and I could not budge it. I put it back in PARK, separated the master cylinder from the booster and put the car in NEUTRAL and it started to roll down the incline unassisted. I put it back in PARK, reconnected the master to the booster and put it in NEUTRAL one more time-it would not move! So, is there a push rod adjustment somewhere or am I looking at this illogically?

Replies:

From Larry:

Yes there is an adjustment to solve the problem you described. On most cars the rod from the brake pedal to the booster (it goes through the firewall) is adjustable. Some cars also have an adjustable rod between the booster & master cylinder. There should be a little free play when the pedal is all the way up. If these adjustments don't work, you may have some mismatched parts. I have seen the wrong master cylinder mounted to a correct booster and the wrong rod at the pedal.

I HOPE it is an adjustment and NOT a parts mismatch!