I wouldn’t do any welding until I saw what its supposed to look like. Maybe a fellow bolter could post a photo!
I agree completely. Also, Even gas welding or brazing is likely to warp the shape of the opening.FWIW, MIG works well for welding sheet metal. But filling holes (or pie cuts) is probably better using O/A if it comes down to them even needing to be welded. If they haven't cracked at the bottom of the pie cut, they probably won't in your lifetime.
