You have too much rust in that area to depend on rust converter alone. I am seeing Swiss cheese at the bottom of the inner-to-outer cowl.
Not the end of the world. I would remove the inner-to-outer cowl from the inner cowl. This will allow you to ascertain how much rust is between them.
DO NOT rush out and order a new inner-to-outer-cowl. They do not fit in any way, shape, nor fashion. Instead, just cut out and replace the Swiss cheese metal at the bottom (the rest is usually sound enough to work fine). If you need a patch for the inner cowl, make sure you buy the short, lower portion panel. The full panels DO NOT fit. They are bent completely wrong and will drive you nuts trying to modify them to fit. The lower half panels fit perfectly (go figure. I can't).
Once you patch your inner-to-outer cowl, sand blast it and prime, and paint it, since much of it will be closed in once you put all of the other panels back on.
Carl
