The other option would be to flatten out the stepped flange, trim and butt weld the cowl piece in for a no filler (less filler?) repair. Many of these lapped and leaded joints were done at the factory for speed of assembly more than anything else. Get rid of the lap, it gets rid of the need for filler. Here's some similar sample "de-leading" and seam removal...


http://www.trifive.com/forums/showpost.php?p=357820&postcount=45


http://www.trifive.com/forums/showpost.php?p=360642&postcount=58