Apologies for introducing myself via a cry for help, but I'm Chris, I'm new here, and I need help!

I've got an orange '74 145 that I'm fixing up for my lady friend. I'm just wrapping up the replacement of pretty much all the suspension and braking components, but I can't get the brakes bled for the life of me. I've scoured the board and seen many tips and tricks to try, but still am coming up short and it's starting to get frustrating. I don't like getting frustrated by something that seems so straightforward - makes me question my mechanical aptitude! This has been "one of those" projects though, and I usually am at it at night after work when I'm a bit worn out already.

The facts:

Girling calipers front and rear.

Reman (Cardone) calipers on both fronts and one rear (the old ones were a mess with the exception of one obviously newer rear one). All six (four front, two rear) rubber hoses are new.

System sat open for several weeks after removal of all the brake and suspension parts for reconditioning, so I started with little to no fluid in there.

When I got it all back together, I made an oversight and tried the "pump the pedal" method for bleeding the brakes. I got nowhere with it, no pedal feel at all, and came to realize with some research here that I most likely ruined the master cylinder by pushing it past its normal operating area and into whatever corrosion, etc. lurked beyond, ruining the seals. OK, so I had debated replacing it anyway while I had everything apart. This car will be a driver so might as well.

So, there's a new FTE master cylinder in there now ($160 from IPD and it didn't even come with a bench bleeding kit!). Bench bled it anyway until there was no air coming out of it and shaft travel was firm. Installed it on Sunday.

Bought a Motive power bleeder and have run several quarts of fresh brake fluid through the system, following the bleeding order in the green book. Rear end is always jacked up higher than the front.

So everything's new, I'm getting fluid with no bubbles at all 8 bleed screws, no fluid loss from day to day, no leaks, but I can't get any pedal feel. Tonight I tried tapping every brake part lightly with a deadblow in an effort to dislodge any air pockets - I did get a bit more air out of a couple bleeders after that, but then completed bleeding (and did it once more) with no luck. The pedal now feels like there's SOME resistance but will still go to the floor if you push for a couple seconds, and once the car's on and the booster is active there's no pressure at all and the car certainly won't stop itself yet.

Speaking of the booster, when I replaced the master I saw some odd fluid hanging out in there. I sucked it out with a mityvac and it was not really rusty, but almost the color of power steering fluid. However, the old master didn't appear to be leaking around the shaft so I'm a bit confused as to what it was and where it came from. Plus, when lightly pumping the brake pedal the engine revs up. Both of these things I'm thinking point to the booster needing servicing, but that shouldn't effect the actual fluid in the lines - and the booster does work currently.

Apologies for the novel, but I wanted to get all the info out there. What am I missing? I've done a fair bit of mechanical stuff on many cars before, but I guess I've never filled and bled an entire brake system from empty. Am I overlooking something simple, or do I just need to keep bleeding the damn thing over and over til that one magic air bubble comes out of hiding (or I shoot myself right in the head)?

Any help is much appreciated.

Chris