Originally Posted by Moon
...If you can lockup all 4 tires then ( in my mind anyway) you've got enough brakes unless you upgrade the tires to the point where they overcome the brakes...
I've been trying to get the rear drum brakes ( 85 Monte Carlo rearend ) to lockup on my 38 Ford PU. The truck stops pretty good but I know it can be made better so that's something to work on this winter.
While I agree that if you can't lock up all 4 that you have serious problems, just being able to lock them up doesn't make for good (or even sufficient) brakes. Try stopping from 80 as fast as you can without locking up the brakes. Then do it again and again 'till the brakes fade and you can't even stop the vehicle. If you can't get at lease a few stops in without the brakes fading than you need more brakes.
As for your problem I think I have a solution. Try using rear wheel cylinders from a manual brake S10 of the same year. They came with larger wheel cylinders and will give you some more rear brakes.