This a brake master cylinder question regarding a 1966 Mustang GT convertible.  The service brake pedal does not easily return to the full out position after making a stop.  This results in the brake lights remaining in the ON position.  What is the best way to spend my hard earned money to fix the brake light problem and improve overall brake safety? 

I have been told the likely cause is that the original, rebuilt brake master cylinder (clip-on cover) is too old and tired.  I have also been told to replace the original single cylinder with a dual.   

A)  It has been recommended to use a Granada (... unsure of year/model ??) dual master cylinder (rather than a 1967 Mustang) because it will provide a bit more hydraulic force resulting in slightly improve braking power/feel, yet retain an "original looking" dual master cylinder.  Is this true? 

B)  Also, I have been told that since the replacement of a single MC with a dual MC is a safety improvement, it will not result in a loss of show points.  Is this true?