If I am not mistaken, part of the reason the car was Cat B was because it required a new chassis; therefore, cosmetic repairs are one thing but structural integrity etc are another ball game all together.
As for cars being rebuilt, 2 RHD have gone to scrap heaven and iirc 3 are re running around with Cat ratings. There are also a few, like the Hammond car, which have seen damage and been repaired. Good examples, with history, are becoming rarer and I think few people looking for an Aeromax will be satisfied with one of the substandard ones.
