For a "correct" restoration, you should delete the side vent. Might be easier to just weld a patch over it and smooth over the welds with some body filler.
If you try to reweld the vent door bracket on, it will likely crack and fall off again. Welding sheet metal is hard enough when you have good access. You'll likely burn thru when trying to weld small sections of sheet metal. Then there's the issue of getting it lined up correctly in the first place to be able to weld it.
