well, i think the issue isn't only the the hole you can see, but the overall condition of the pipe interior. in other words, there are probably areas of the pipe that are almost rotted through all around there.
i just had a friend, who is an expert metalworker, patch the holes in my pipes. i watched him do it, and the metal all around the holes was so #$%*ty behind the chrome (impregnated with rust and oils), that he had a hard time getting a clean weld.
if you are going to weld, i'd say do what he did, which is use stainless sheet and bronze rod. after a bunch of work, the end result does look great, wont rust instantaneously (mile steel will), and will probably outlast the pipe itself.