Gents, by way of an update, I re-bled and tested the MC. Passed. I checked shoe movement on retract, does not appear excessive. Tightened up rear adjustment. No change.

Yet another Vac pump bleed. No change. Traditional pedal bleed, no change.

It has to be air in the system....

Did an overnight gravity bleed on the rears, and the fronts are bleeding today. I'll let you know.

One other thing I touched on, but I had been running an old MP adj prop valve on the rear output side of the funky 73 prop valve with the shuttle valve in it. I replaced that mess with one of the Willwood adj prop valve/distribution block combo units. It gives far less adjustment on a per-turn basis than what I had. I have it set to max rear flow for the gravity bleed.

Also, to install that wilwood valve and my big exhaust, I had to get a couple of 10" prefab brake lines and bend them to my will. I checked and verified the integrity of the bends, but I theorize given my routing, they could potentially be an air trap. Hopefully the gravity bleed will deal with that, if it is the case.

Sure would be nice to have access to a hydraulic brake mule like I had when I worked in hangars.