You have an original motor in a pristine Firebird.

The quick "get me home" solution is to cool, clean and JB weld it. Or tack a weld bead.

I would seriously replace the pan and take the old pan and inspect it real well. Probably nothing too severe, but if that pan has one pin hole leak, how well and for how long do you expect it to hold up?

I am pretty sure there is a thick metal plate inside the oil pan where the oil drain plug threads into. If the weld went in too deep from the inside (when produced) could promote moisture and rot, and eventually failure of that entire drain plug area.