disc brake pedal low

{I don't think this is a bleeding problem. If it was you would not be able to "pump up" to a good pedal--it would still be mushy.

I think either the rears are too loose (adjustment) or the master bore is a mismatch to the disc/ rear cylinder bores.}

Then I will just leave the mechanicing advice to you, I don't know notin anyhow after 33 years of turning them wrenches. I'll just be over here mindin my own busniss.

With your hostile attitude, that might just be a great idea