I know some will cringe at this, but if you get ALL the rust out, neutrilize the metal, you can lead over pinholes & some pits, much easier to shape, no blowing through the weaker metal & it should hold up over time, now this is not for major rust, I cut out tons of that & replaced with welded in patches, but for a few pinholes I "think" it should be fine, key word is think, I'm not a pro! Rich.