As already said anything is possible. It's unlikely Karman would have converted a single car or even the odd few and it definitely would not have been done on an assembly line as that wouldn't be possible. I suppose SVE may have had the capability who knows, not sure why the Police or Military would want a Cabriolet. I know sometimes Government bodies or Royals cars were registered to the authorities and SVE certainly adapted cars for Royals as one offs. Lady Di had a cabriolet but believe it was a metallic red MK3. The problem you have with changing cars from the norm is warranty because nobody recognises it nor knows what to do with it, this is why they leave to the dealer usually. Somebody inside Ford has said that SVE enjoyed working with the Cabriolet. I have some prototype images, the original mock up looks quite different. Sadly I cannot share these.