Epoxy putty can be used to make a fairly long term repair. Welding in new metal will be longer lasting.
How much collateral damage do you want to suffer to your paint should be explained too.
MIG welding will damage out about 2 inches. I know this to be true as I just welded in a small 1 1/2 inch by 3/4 inch piece to repair my corner, for what started as a pinhole. It wasn't easy as the factory brazed in the corner and the MIG welding just kept melting it back. Finally got to some steel and finished.
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Redrum (or Mike)
68 Corvette - 383 CI 427 HP
69 SS Chevelle being updated to Pro-Touring
97 Z-28