A couple quick thoughts here. It is funny about perseptions. Here in the States there is a perception that there are better deals on cruising boats in Australia and New Zealand than there are in the States. A few years ago I helped a gentleman who wanted to buy a distance cruiser on a tight budget. He ended up buying neat little custom built cruiser in New Zealand. The funny part was that his perception was that there were far more choices in Oz and NZ than there were in the State. Never having been to Oz or NZ I can't really say whether he was right or not.
With regards to your list of potential choices, I would suggest that you remove the Triton 30 from your list of candidates if you are looking for a traditional long keel cruiser. The Triton 30 was a much later design, an adaptation of the Bayliner Bucaneer 30, which was a pretty poorly built fin keel-spade rudder IOR era cruiser-racer.
I somewhat question the posibility of buying one of these boats and putting her into offshore capable condition. Wwhile most of these boats have been adapted for offshore use and have been sailed successfully offshore, for the most part, the boats on your list began life as racer-coastal cruisers. Most are 35 or 40 years old boats and one that you would find for sale in your price range is likely to be very tired and in need of serious upgrade before going offshore. Even doing your own work, it would be easy to drop $15-20K into bringing one up to condition and equipment level that would make one suitable for "crossing oceans".
In other words, as would be the case with almost any boat of that age, you can expect to have to do a lot of deferred maintenance and upgrades before going offshore. Like any boat from this era, boats of like these are likely to require some combination of:
-New sails designed for offshore use,
-Engine rebuild or replacement,
-New offshore capable deck hardware and
ground tackle handling gear,
-Reworked electrical system (These boats were built before tinned wiring and with exceptionally simple systems),
-Windvane and/or electronic
autopilot,
-Upgrade or replacement of chainplates, mast step and associated suporting structure, standing and running rigging that are beyond their useful lifespan,
-Replacement or rebuild of worn out or out of date deck, galley, and head hardware,
-Worn out upholstery,
-Non skid in need of renewing,
-Out of date or totally absent offshore style safety gear,
-Electronics that are non operational, or in need of updating,
-Thru hulls and seacocks in need of replacement,
-Blister, fatigue, rudder, rotten bulkheads, failed tabbing, hull deck joint or deck coring problems
-Keel bolt replacement (bolt on keel) or delamination of the hull from the ballast for a glassed in keel.
I also want to strongly support Moe's suggestion regarding the late 1970's era Southern Cross 31. (Newer versions are out of your price range) If you are interested in buying an inexpensive, small, traditional, long keel, offshore capable singlehander, the Southern Cross 31 is about as good as they get. These boats were designed as no gimick offshore capable designs. They came with sensible rigs and good tankage. They have enough displacement to carry the kinds of supplies and gear required for offshore cruising. Although very simply constucted, Ryder did a really nice job building these boats to a higher standard than was the norm. Most had diesels from the factory. Their outboard rudder is very adaptable to a simple home built trim-tab servo type self-steering vane. One shortcoming that I came across with these boats is that they had a fiberglass fuel tank which did not hold up all that well, allowing some diesel seepage over time.
I would also suggest that you add the similar concept Allied Seawind to your list of candidates.
Good luck,
Jeff