Need some brake help please!1982,C-30

[100%Chevy]

I'm reworking the brakes on this thing.I've replaced the front rotors/pads,the rear wheel cylinders,drums and shoes.Plus the long brake line on the rear housing.
The rear brakes didn't work when I bought the truck.The fronts barely worked.
It has hydroboost and now the fronts work o.k.(need more bleeding).
The master is not new but I do have pressure on the lines.
I can't get fluid to the rear!
Do I need to somehow by-pass the proportioning valve?Or,the one at the rear?
Thanks to anyone who can help!
Mike.

[Shugalou]

Have you verified that the prop valve isn't closed?

Take a test light to it to verify I can't remember if it illuminates when it's out or not...but if you check my previous posts you'll find I cover a lot brake issues I had when rebuilding mine.

Also I recommend building a pressure bleeder. Hatzie helped me out with that decision.

[100%Chevy]

I'll test the valve tomorrow.
I can pump the pedal about 10 times,then look in the master and see fluid pushing back up.
Taking the line loose leaving the prop valve,I can't get fluid out to the rear.
I may build a pressure bleeder.I have some 1/4" aluminum that should work.
Thanks for your help!
Mike.