After much effort I am 90% sure that the new disc brakes have been bled properly. Using the Phoenix injector was the final fix for me.

However, it was 3-4 years ago when I installed the new booster and MC. The pedal is not spongy at all. But when the car is running, the pedal goes all the way to the floor before the brakes engage. I wonder if having installed the shorter push rod would cause this, or would they even engage? I seem to remember installing the shorter push rod (the one on the MC side) but I can't remember for sure.

Did you add or replace the booster?
There are 2 holes for the rod on the pedal side depending on app.

if you are talking about the rod that goes from booster to MC there is a long and short one. Your MC is what determens which one you need.

Hi Miles! usually it comes with two rods.....and you will pick one. So maybe picked the wrong one.

This booster was replaced by the one from the kit I received for the front discs. Yes, I remember that it came with both rods. I just wasn't sure about whether the short rod being too short would cause the problem I'm experiencing. In the meantime, I ordered the long rod since I have no idea where that might be after two moves in the last 5 years Once it's here I'll wrestle the master cylinder away and see what's up.

betcha thats it, heard of that before being the case....but of course there 'can' be other things too...

They'll be working so good I'll need to get those shoulder belts installed asap

Dulp!
Reread original post. Never mind...

The short rod was installed. However, there is also a removable plug in the master cylinder that when added to the short plug equals the length of the long rod. Not sure what to do now but I suppose replacing the master and booster as a matched set wouldn't hurt anything but my pocket book.

Two thoughts,
Are your rear brakes adjusted out as far as possible? If the rears are way out of adjustment it takes a whole bunch of fluid to push the shoes out with the pedal traveling a long way until you get pressure. I know the front and rear are separate but it still affects brake pedal travel.
Did you get the correct diameter MC? Most manual MCs have small dia. pistons. This gives you more pressure with the same force on the pedal due to the cross sectional area of the piston compared to the larger power MC. The power MC has a larger cross sectional area piston and moves more fluid with the same travel as the smaller piston. The mechanical advantage of the smaller piston is not needed due to the power assist.

They came together as part of a disc brake kit and they do seem to fit together. Anyway, I have ordered a replacement pair. Before long I will have completely replaced that kit. I had bought it from a former ebay seller, and it was always suspect in the back of my mind.

New master/booster fixed the problem. So, I finally have pedal! Another bleeding and they should be good to go.

Good one.
So you have the shoulder belts on order?

I have them in a box. Not sure if I will actually find mounting holes under the headliner.

feels like the mount is moving under the headliner. i can hear something metal rocking around in there. i guess i will wait until it's time to replace the headliner.