Catalytic Converter on a 65 Slant 6?

This may sounds crazy to many... I am trying to figure of ways to have my daily driver 65 Dart GT not smell terrible.

Has anyone added a Catalytic Converter to your pre-smog Slant 6?

Or does anyone have any recommendations on how to make it burn cleaner? I have electronic ignition, new exhaust, it is tuned up really well, has no mechanical engine problems - it just smells like a old lawnmower when I am sitting in traffic.