Catalytic Converter on a 65 Slant 6?
If you really want to clean up the exhaust, get rid of the carburetor and install a fuel injection system .
FiTec offers a 1 barrel , 2 barrel and 4 barrel system that are self learning . Of course you will also need a fuel system upgrade .
The result will be cleaner exhaust , better mileage , better performance and easier starting year round.
Don’t install a Cat unless you do this first .