New brake system - no pressure...

I'm looking for some insight here...
I just replaced my whole system. I went with a standard Cardone master, early 70s factory disc / drum distribution and proportioning block, and no name roll control. After chasing a bunch of leaks around I have everything tight, but the system will not pump up more than just off of the floor and bleeds down in a few minutes. I bench bled the master cylinder before install and once after in the car. I pulled the master and inspected the seals and they look fine. Can this be a junk master or am I missing something? I'm contemplating just buying one of Dr Diff upgrade masters with two bolt adapter.
Any thoughts?