Aren't you using the original brake pedal arm and doesn't it hit the lower toe board to stop it's travel? What's the difference between now and when it was a single pot MC? The pedal/arm has to return and bottom out against something so you can adjust the rod to allow the MC piston to fully retract.
Mike B
The original brake pedal arm does not hit the toe board. It is held at a specified distance from the toe board by turning the threaded clevis thus adjusting the length of the pushrod.
The problem the OP is having is that, unlike the original master cylinder, his Corvette master cylinder does not have a captivated pushrod. There is nothing to prevent the brake lever return spring from pulling the Corvette pushrod out of the master cylinder.
