You don't mention if you have hooked up the booster or not. Without the booster operating, you won't feel much. With power brakes you have three things to worry about having right, 1. No air in the system, 2. brakes are mechanically good and properly adjusted with no leaks, and 3. Manifold vacuum. You should have at least 16" up for good brakes. If you have an L6, your vacuum port will be on the intake below the carb and on the carb base or just behind the carb on a V-8. Don't kink the vacuum hose.
Best wishes,
Les
