I wouldn't be concerned a lot of with regard to the fin on the bottom, just seal it up so it will not leak. Ironically I welded up a lower unit just two days ago. Dude hit a rock and punched a hole within the entrance of his unit, dug https://key-west-boat-upholstery32109.tinyblogging.com/top-latest-five-on-location-lower-unit-repair-urban-news-75244435