If you could purchase this car that is pictured in your last post, and use that entire body you would be way ahead time and money wise, rather than fixing the one that the roof and side are so badly damaged. If you want an ambulance, you would be way better off purchasing one that is complete and drivable than you would be attempting to resurrect the damaged one. You are free to make your own decision as to what direction you will go, however, you should also weigh the information that has been presented to you by experts in the field of repairs, and the advise that they have given you. I believe that in the end, even if you find a roof, that the structural damage to that vehicle renders it almost impossible to repair successfully, and in the end, you will have way more invested into the project and in all probability it will never be finished. I offer this advise not to discourage you from restoration, but to save you the anguish and money that will be wasted on this particular project. For years now, all the people that have been involved in restoration projects have almost always given the advise, "start with the best car that you can afford, and know when to walk away from a car that is going to require more money than your available resources." While we have no idea of your financial resources, I can clearly state, that this project is going to take more financial resources than it will be worth in the end, by more than 3 or 4 times. When I was in the business, I took on projects that were more damaged than the average shop would consider, and I also learned the hard way that in the end, there was a reason that other shops turned down the job. My best wishes to you, no matter which way you decide to go. Just don't loose sight of your dream, but consider all the facts as presented.