Super Stock Springs for the street.

I purchased a pair of Super Stock springs for my 1969 'Cuda. Since the car is missing it's original big block I am using a 340 with the 4-speed. I have heard good and bad about the Super Stock springs on the street. With my motor and Trans should I bother changing them? If I did change the springs should I hold onto the originals in case a purist wants to have them with the car?