John, I liked your post. After I posted the pictures, a newbie myself, I later saw a post in very old forum archives that already mentioned the possibility of the first aid kits at the Seven site. I still look for examples from time to time on ebay.
I think it is helpful that you have a contact from the company. I'm interested to hear what they have to say. Dimensions, type and number of rivets are what I was trying to find out. Also if there were washers under the rear mounting clips on the box. And if the mounting clips had a strap that could be attached. And details of the construction of the box, for example if they had a wire that went around the edge of the lid or opening. If they had layers of metal that were folded over the wire as shown
here to form a rounded edge.