You mention that you have had to change the distributor cap often, How often is often? You don’t mention any performance issues such as hard starting or misfiring. Are you changing the cap just because you don’t like the look of it? If that’s the case ,buy a new cap and keep it in the car along with a screwdriver to change it with but wait for a performance issue to change it.I had a 72 Impala and never got more than a year out of a cap. It was two cars in one, my first Chevy and my last.