Another "brake help" thread...

• I'll pull the speed bleeders. I literally put them on three days ago so they are not part of the problem, but I hear you.
• CV lines are not crossed, I've checked multiple times. Also haven't touched the CV except to replace the front drivers hard line from the CV.
• I've bled the brakes so many times, and every time but the most recent (after the off the car bench bleeding and speed bleeder install) it's been in the correct order. Most recently was just the fronts again, but worth going back through to be sure.
• Caliper retainer clips are torqued to 15 ft-lbs per the FSM.
• Retainer clips, anti rattle springs, rubber bands are all new (are rubber bands necessary? I doubt that's my issue up front because they don't touch the calipers).
• Front pistons might be retracted too far, calipers are brand new though. Any way to test?
• Rear shoes have been adjusted multiple times, every time I pull the drum in fact because I'm burning through the shoes. But I'll do it again.
• I'll inspect the flex lines again. These are braided lines and not likely collapsed being they too are brand new from Bergman. Being braided lines, anyway to know for sure if they are collapsing? I could see a kink in a braided line causing an issue, but seems like I'd actually see the kink. I'll get the car on ramps so I can see the lines while I cycle the suspension and steering.
• I do not have a high hard pedal at all. In fact, I'm 75%-ish stroke before I feel a level of resistance that indicates (to me) brakes engaging. Then a couple more pumps and I have the kind of pedal I expect.
• Looking at the trouble shooting flow charts in the FSM, they point to proportioning valve (not new), rear brake hardware being weak (maybe, but new), frozen pistons/contaminated linings (maybe, but new), and then of course air in the line (maybe, but I've bled everything multiple times).

All that said, I'm at a loss as to why I have almost no pedal w/o at least 3 pumps, super loud rear brakes (once they're pumped up), huge amounts of brake dust on the rear with virtually nothing on the front, and occasional rear brakes sticking. I'm curious, is there a way I can test to make sure the front calipers are sliding? Is it dumb to pull a pad and hit the brakes? Is it dumb to pull the drum and hit the brakes to see how/if the shoes are retracting? The FSM shows a great set of gauges to test pressure in and out of the CV, would love to do that but can't find anything that looks like I can T into the lines. Any other ways to test the MC/C-valve?

Thank you for the feedback so far.