Ok everyone...brand new here but I was referred to this site by a local so here I am. I converted my 72 Cuda with 4 wheel manual drum brakes to 4 wheel power disc using the right stuff detailing kit. Everything is brand new except the original distribution block, all lines and everything. The block was pretty cruddy, I cleaned it as best I could and reinstalled it.

Car stops on a dime, pads/calipers release and wheels roll as normal. The problem is the pedal is not fully returning to it's proper resting position and I have to pop it up with my foot to get the brake lights to shut off. Another symptom we've noticed as that once you pop the pedal up while sitting at idle, the engine jumps up about 100rpm to it's proper idle speed. Anyone else experience this? I unfortunately haven't had much chance to mess with it due to family commitments but I plan to get it back on the road this spring and I'd like to have a few ideas to check before I drive an hour to where the car is garaged to work on it. Could the distribution block be causing this? Could the new master/booster possibly be bad? Maybe something needs adjusted that I'm not aware of? I have the pedal adjusted about as high as I can get it and the brake light switch all the way forward.

Well, if you are using a front disc, rear drum setup, the car needs an actual "proportioning" valve. The distribution" block has no proportioning in it.
Secondly, did the pedal return to the top of its range of travel before? I had a 72 Duster with a sticky brake and clutch pedal. That turned out to be due to rusty scale on the swivels where the pedals swing.

He's got 4 wheel discs.

Odds are the booster is the issue solely based on the RPM of the engine changing (thinking vacuum).

I seriously doubt the distribution block is causing the pedal to stick.

How did I miss the 4 wheel disc part??? I must have blinked.

I didn't think the block would either but being that it's the only part I didn't replace it made me wonder...if I'm correct there's no moving parts inside of it.

A few people on another forum suggested checking the pushrod arm length on the booster, honestly I didn't even notice it was adjustable. I'm going to start there and see.

Haha yeah. I do have an adjustable valve on the rear line but it's wide open.

That would have been my first suggestion....020 up to .060 max airgap