72 Demon spare tire well replacement

I have decided to replace the spare tire well in my demon. It has some rust pitting with light holes and I have decided to replace. I have the entire well but I only want to replace the bottom it possible.

I would like to get some idea on how some other guys have done this in their car.
If I have just replaced the base of the spare tire well what is the best way to put it in there. Do I tap the replacement one on the inside of the existing opening or do I put it in from the bottom? Do I weld it from the inside or the outside?

Let me know what you guys have done...

Thanks,

Craig
Author: admin