Try a search above on "inner cowl" (use the quotations).
It will return these results. Not all the links will be appropriate, but some should cover what you looking for:
inner cowl (different lengths of panels),
outer cowl (different lengths of panels),
inner-to-outer channel, etc.
Post links to photos, and people will be able to better advise you.
This is a commonly needed repair. There are a variety of possible pieces, depending on the extent of your rust.
