Chris,
205/70 x 14's will give you an overall diameter close to the original. I think that this size looks nice on a 65-66 car. The BFG Radial TA with the raised white letters is a great looking tire with the Magnum 500's.
To get a similar diameter in a 60 series tire, you would have to go with a 235/60 x 14.
The sizes that you mentioned would have a small overall diameter (tire would be too "short" looking in my opinion.)