No rear brakes after 4 wheel disc swap?

Appreciate all the feedback.
So today I plugged the reservoir for the front brakes. Then the pedal had no resistance at all until 3/4 the way to the floor then it stopped with no give. I was thinking maybe the line going to the rear was blocked up with debris so I pulled one of the banjo bolts out of the rear caliper and had someone push the brake pedal and there was fluid pushing so I am getting fluid to the rear calipers. But at the same time no fluid is purging out of the bleeder. So then I put new rear calipers on since the old ones were out of a junkyard and no fluid was purging. But saw no change.

. As far as the 8.8 ebrake goes I opted to leave it off and pitched it back when the swap was done. I don't really see how it could have had any effect on the caliper but may be wrong. And the 8.8 is out of a 1998 explorer with disc rear if that helps.

I'm thinking of ordering the Dr. Diff kit with all new prebent brake lines and dist block and the correct master cylinder just to eliminate these out of the equation but seem like itd be a pita fitting all the new lines since the motors in the car and all.
Just my thoughts and where Im at currently.. Thanks for the help