How rare is this and what's it worth?

...but is fairly solid body wise from what I've been told.

Looks can be very deceiving. Convertibles usually rust from the inside out once the top starts leaking and the carpet gets wet. Mine looked totally solid from the bottom. But when you peel up the carpet, that's when you find out what you really have. Also inspect the trunk carefully. The lower rear quarters and the trunk extensions are the first to go.