In case it works out I don't want or need the bottom cowl louvers, I wanted to have a way to cover the hole. Secured the original cowl cutouts with bondo & sticks, then glassed a flange to them on the inside. After cure, popped out the filler blank and trimmed.
Original louver cutout section held in place with bondo & sticks
On the inside, I glassed 2 ply BID tapes to the cutout and the cowl flanges.