I was lucky with mine like that, my wind shield gasket had cracked and shrunk, letting water seep in. My hat {AC Car} was intact. Never did figure out why the seat riser rusted out worse than the pans......
I have looked but didn't find it yet but there was a thread where someone used the panel adhesive to install patches from the bottom. Can't remember who it was though.
I appreciate everyone's perspectives and ideas - this is awesome info and gives me just a little more "peace and hope" about the cowl leak (no "love" yet though - LOL)
I've seen it done this way on Mustangs. It's the way I'd do it. You have to be able to weld pretty good for it to work....or know a good welder. This is one example [nomedia="http://www.youtube.com/watch?v=t2fK8PN4-T0&feature=related"]65 Mustang Part 15 - YouTube[/nomedia]