<VV> Weak brake action

[Charles McKinley]

I'm a little embarrassed about asking this, as it seems like a moronic  
question, but I'm at a loss as to where to go next. I've had a '63  
Monza 900 for about 16 years now, and in all that time, the braking  
action is what I'd call puny - maybe I've gotten used to the power  
brakes in every other car I've owned for 40+ years, but it really  
doesn't feel right. The symptoms are that when I apply the brakes,  
they do work, but I have to apply more pressure than I think should be  
necessary, and there's no such thing as a panic stop - I can't jam on  
the brakes and screech to a halt (that's the most worrisome part.)

Recently I've done the following in an attempt to fix this:

- had all drums turned
- put in all new brake shoes
- put in all new wheel cylinders
- put in new brake line hoses
- installed new return springs

Long ago I rebuilt the master cylinder.

The brake pedal is very solid - no fading, solid stop with minimal  
depression

I have a complete set of new brake lines, but when I learned you have  
to drop the motor and remove the gas tank to install them, I decided  
to hold off until I have a more compelling reason to do either of  
those chores.

I've bled the master cylinder and the wheel cylinders until I'm blue  
in the face, with no improvement.

The only items left in question (that I can think of) are:
  - master cylinder problem of some sort (can't think what)
- old brake lines being a little plugged (although I get plenty of  
flow when bleeding the wheel cylinders)

Any suggestions?

Thanks in advance,
Chuck McKinley