That's a cool boat very similar to mine, I have an old 8hp outboard that I use on it. I've only sailed pretty slowly on it so far. But winter time here in florida is also the windy season and best for sailing so I can't wait to sail more often. There's alot of old hardware and stuff that kinda worries me, I wouldn't want to push it quite yet. I got a job just two days ago assembling power boats so I can make some cash to pay for some new stuff. I bet australia is fucken awesome hope to visit there someday.
Here's the actual laws on that:
Abandoned Vessel Claims Process FAQs - http://myfwc.com/boating/waterway/derelict-vessels/claims-process-faqs/
Good luck doing it that way, and if you do your gonna spend alot of money with no guarantees. However, If you could tow the boat to somewheres private lol and make some modifications like removing the serial number. You could maybe, sort of, possibly claim you built the boat and get a title for it that way. Otherwise it's like riding in a stolen car, because Florida considers it is a stolen boat. You can find cheap old boats on craigslist like the one I have fairly easily enough.