brakes not working as expected....HELP

[Steve-W]

So when I bought my 1969 c10 it had drums in the front and drums in the back that were closed off by the PO. there was no brake booster. so only the front brakes were there to stop it, which is like trying to make an emergancy stop with a 1000 Feet oil tanker...

I bought a complete 73 crossmember including disk brakes. I also installed a new master brake cylinder with booster. put in a new brake balancer, one tha as I was told should be for a disk/drum setup, the rear brakes are all new and the system was bled to the point where my brake pedal is rock hard.

so far so good. last Friday I finally got to the point of the first test drive and boy, was it a major downer... the brakes are nearly as bad as before.

my conclusion and I'd love to hear your opinion:
1) the brake booster isn't working..but how do I test that, because we checked whether the vacuum is good and it is.
2)the brake balancer is somehow messing things up?
3) I got the plumbing on my master brake cylinder back to front, but I cannot imagin this having such an enormous impact seeing that surface times power is pressure and the two chamber don't have such a big difference.

am I overlooking something?