1991 ranger brake problem

While checking and cleaning the brakes I was interrupted and on returning I pushed the brake pedal by hand without a rear drum installed. Naturally the pedal went in all the way. I checked the wheel cylinder boots, found no fluid, installed the drum and vacuum bled all 4 brakes. Now the brake pedal goes to the floor with only spring resistance. Using a broomstick, cord and pulleys to press the pedal, no fluid comes from a disconnected master cylinder port though it can be vacuum bled freely. BTW the master cylinder flare nut thread is 10mm-1.0 while the wheel cylinders have inch thread.
Yearly LPS-3 let all the bolts loosen but the master cylinder is frozen to the booster so I haven't checked if the pushrod moves, maybe tomorrow the Kroil will have freed it. I don't know if my back can take the contortions of crawling under the dash to check the linkage there, which was pushed beyond normal though with only one hand.
Has anyone else had a similar problem with an early 90's Ford Ranger or Explorer?
TIA, jsw