Another spongy brake pedal

[JT1930]

I don’t come on here much at all anymore asking questions but this one is killing me.
Brake pedal is spongy and goes to floor.

System.
-Boling bros Lincoln style brakes.
-3/16” brake lines
-‘67 mustang dual pot drum/drum 1” bore MC
-willwood 10# residual valves.
-tee for brake lights.
-shoes aligned and adjusted for slight drag.
-dot 3 fluid

Yes I’ve done a search and have tried everything I read on here and ford barn. Ive pretty much done every method of bleeding under the sun. Latest method I’ve done is as followed.

- Re-bench bled master cyl. Good no bubbles.

- Cap rear port. Bleed fronts first. For stiff pedal. Hand vacuum first then pump pedal and hold bled. Good.

- Connect rear brake line to MC. Vacuum bleed first then pump pedal and bleed. Good.

While bleeding I notice a stream of small bubbles coming out of all 4 bleeder. Thinking it’s the bleeder letting air by threads but have a bit of teflon tape on them to try and reduce that.

After all bleeding is done push pedal. Feels firm. Promising. Goes about half way down and gets firm. Move car back and forth pedal basically goes to floor but stops car. Jam on brake pedal stops car but not fast enough. Park car pedal gets firm as before moving car.

Suggestions? 1.25” bore mc? Should I just can the dual pot for a single ? Help !

Pictures are attached to just show if lines off master are what is causing air in system still. Rear backing plates are nothing new of what others have done when using model a rear end.