Jacques,
I flattened the old battery box this afternoon. Had time on my hands because the mains power went out for most of the day. Swines!
Anyhoo, got to making the template for a new one, and I will investigate this & hopefully buy the correct gauge steel sheet to commence the building.
Here is what the template looks like. If you are interested, I can post it to you once I have scribbled onto the new steel sheet.
I know it fits into place exactly, and all the holes line up. At least they do for the individual sides when laid on the base, which still has all the rivets sticking up. Best you check for yourself if you are wanting to use it.
Do you have the correct battery securing bolts? If not, here is an indication of the sizing, in case you need to make them.
In the last photo you can see one of my original wing nuts. It is made of brass. I only have the one, unfortunately. Search begins for a second one. Guess it's brass so any acid doesn't affect it???