I have posted this problem before, but have made a change to the vehicle which created minor improvements. After performing a rear wheel disc coversion the first 2-3" travel of the brake pedal is soft. Brakes are being applied but pedal feels funny(too soft). Front brakes apply first and rear brake apply after another 1/4" of pedal travel. Brake pedal does not become hard untill half way through its travel. I also have a 66 Corvette with manual stock four wheel discs, pedal is as hard as a rock as it is immediately pressed. Looking for the same feel.
67 Camaro
Small piston front GM calipers on all four wheels (79 Monte Carlo style)
68 Corvette manual disc-disc master cylinder (This was recently changed from a manual disc-drum master and pedal feel improved)
Stock manual disc-drum proportioning valve
Thank you for your help