The first thing is to figure out what the engine presently was. The second thing would be the transmission is not original to the car. Cast iron powerglides is not difficult to find, but finding someone who knows how to work on it is. They require specialized tools to repair them. I see a box on the floor, but no compressor, so all I can guess is that it is a swamp cooler. It is a project that I could undertake, but not with the starting price of the vehicle itself. I can clearly see it costing $15 or $20,000 to make up cabinetry and everything else that it is going to take to bring it back to what it originally was. Too much work and expense because when you are done, you probably still have a $30,000 car if you are lucky. I doubt that most ambulances of that vintage will bring the kind of money that it takes to restore them.