Update:

After the 1st MC being a dud, my buddy had his store deliver one that hadn't been opened and I swapped it out, setting the pushrod clearance and bench bleeding on the car. He also sent a loaner brake pressure gauge kit.

What I noticed, 1, the 1 1/32" cylinder is noticeably smaller in diameter and 2, the 1 1/8" cylinder holds roughly 1/2 again as much fluid and has a longer stroke. When I was complaining about the pedal only going half way down, it was the cylinder. It now goes to the same point it always has.

After bleeding the system yet again, way better initial bite and much more speed scrubbed off before the pedal bottomed out. I used the brake pressure gauge at all four corners and at each corner, the pressure spiked, then bled off as the pedal went to the stop.

On a hunch, I grabbed the flex line on the RF while wife helper pushed the pedal, the line swelled up in the middle like a snake that ate a rat. The LF and rear flex lines swelled as well, though not as dramatically. I have encountered this on other cars, but never on flex lines that "looked ok" on a cleaning and static visual inspection.

I think I found the problem. I've ordered up some flex lines, and I can't imagine they will not fix the problem.

I've had this car (3rd owner) since 1988, and it has done a lot of sitting (he fluid that I initially flushed was cloudy brown and full of little black chunks). That said, I've put about 80K on it over the years as it was my daily driver until 96. To my knowledge, only the shoes/pads have been changed until this summer when it got 2 wheel cylinders and one caliper, as well as an MC (the one I think is original puked out the rear and ruined the paint on the lower part of the booster) and the prop valve, which has given me fits since the Clinton administration. All of this started because I had to pump the pedal when braking and had no rear brakes.

I shall report back after the install and One More Bleed. I need to buy stock in Prestone.