The back system is not connected to the pedal
Now disconnect the front master cylinder and then connect the back MC and bleed the rear calipers. Then connect the front and you should have hard pedal. The brake bias bar moves around alot when only one MC is connected.
Then make sure you adjust the brake bias bar is adjusted this way so that you have more front brake pressure than rear 2/3 front 1/3 rear
Tony
Unique 427 #4279480 Precision Engine Machine Company 427 s/o 483.47 stroker close ratio toploader 3.31 jag rear