Hi Tim,
The designer of this boat, Bill Lapworth, has a good reputation and the boat looks to be well-maintained, apart from the engine that needs work and besides, is gasoline (petrol), not the ultimate choice in my opinion, due to the risk of explosion, though some people are happy with it. I think a small lightweight diesel engine would be a good upgrade. A number of Cal designs have made tradewind ocean passages. I think you could sail this boat to Hawaii and on to Tahiti with a few upgrades, such as a good windvane selfsteering gear and ground tackle. If you kept the original rig, you'd want to take the mast down and check everything for ocean passages, probably replace the wire and mast fittings etc, but for your first season in local waters, I think you could just get on the boat and go. Make sure you treat that gasoline engine with caution though. I've seen two gasoline engines explode on boats and it wasn't pretty. I also think this boat would convert to a junk sloop very nicely. I converted my boat, Arion from bermudian rig several years ago. Good luck
PS: Things to check are the rudder, which can get tired after a lot of miles under the keel, and the keel itself. Check the floors (structural members tying keel to hull, keelbolts if it has any (not sure if this keel is bolted on or part of the glass hull, and signs of any cracks where keel meets hull.