the pedal goes to the floor and I already changed and bleed master cylinder

Did you bench bleed the master cylinder first?

yes two different new master cylinders, checked for leaks in the lines, checked calipers, and the rear drums with no apparent leaks...

But did you bench bleed the master cylinders before installing?

yes

This will need bled first with a computer like a snap on motus and then bleed all brakes.

what is bench bleeding mean

bench bleeding is getting the air out of the master cylinder before it is installed. then bleed the system starting at the right rear, left rear, right front, left front