Was the boat winterized? Many abandoned-neglected boats weren't. I would pull the intake and check the lifter valley, and the underside of the water passage in the intake. The iron marine intakes rot out even if never frozen

For the outdrive/ gimble ring and transom parts I can highly recommend:
JR Marine - BMAX Sales & Service - Specialty Bravo Tools

I ordered everything from Ron. Awesome guy to deal with. Prices were good. I ordered pretty much everything needed to make it like new in the back (w/o opening drives) when I installed ext steering.. Received a BIG bag of parts and not 1 mistake.
Doesn't get any better than that.