As long as the keel is in good shape, that shouldn't be much of an issue... they're beautiful boats IMHO...
If your buyer is an Aussie, he can not USCG document the boat, as only US CITIZENS can do that. Also, it isn't very expensive to USCG document a boat. The fees can be seen here, but a non-commercial exchange of a USCG documentated vessel is only $84, and there is no fee for renewing it annually. If a state registration is $25, then in four years the "expensive" USCG documentation has paid for itself.I just sold my boat (US Documented) to an Australian. He will state register it in RI while he sails in the US for a few years (the sale was in the state of Rhode Island which has no sales tax on boats). Each state has different rules so check before you buy. US state registration/title is perfectly acceptable everywhere in the US and in many other countries. The only obvious downside is you have to put 3" registration numbers on your bow. Frankly, most boats of the price you're considering don't spend the extra for CG registration.
When (and if) my buyer sails her to Australia he would have to pay Australian VAT tax - but that's a long time from now.
There's no problem working on your boat or having a boatyard work on it (assuming you remember to pay them). Many boatyards will require that your boat be insured - but you will be able to purchase that just fine.
Preparing a boat for a safe Atlantic crossing is expensive. Getting from the US to the islands demands considerably less of both the boat and the skipper (although it is still very much a blue water passage).
If you haven't seen it, John Neal has a great list of blue water boats. Here it is:
http://www.mahina.com/cruise.html#boatstoconsider
Carl
I don't know about US documentation but boats and ships all over the world are flagged from ports all over the world with not a single citizen from the flag country on the ownership papers.
The Taliesin, owned by Lin and Larry pardey flies a Canadian flag, the owners are living in New Zealand and I am not certain of where they get their passports.