BH799, I'm writing this to you from the States where, as you'll probably know, there is a very large fleet of single engine piston aircraft. Your 'discovery' - an appealing plane at a distant location, at a good price but not flown whatsoever for several years - is a common trap door over here. I would advise great caution. And I think I do understand your dilemma: SA probably doesn't offer you the a/c for sale that you'd like to find. When we sailed out to Oz from the States, we put our boat through Customs at Brisbane because it offered an active group of potential buyers who would fly in from yachtie strongholds in cities like Adelaide, Perth and even Melbourne. These were sailors who wanted to cross an ocean, their home port pickings were slim in number, and so they came to Bris and Sydney to shop the new arrivals that had already proven their capabilities at sea. And if that meant the cost of airfare and a hotel room, they'd make the shopping trip into a bit of an adventure as well. (As it turned out, we sold our 13m ketch to a couple who just arrived from the Falkland Is. of all places!) So I'm sympathetic to your plight.
The best planes here often get sold by word of mouth without being advertised. E.g. someone looking for a specific model will be connected with its type club or perhaps an owner or two of that same model, who will have their own grapevines. Most single engine piston a/c are sold by their owners via listings like Search For Aircraft & Aircraft Parts - Airplane Sale, Jets, Helicopters, UAVs, Drones, & Aviation Real Estate | Trade-A-Plane because the prices are low enough that they don't easily cover a broker's commission without inflating the price too much. But for a mix of reasons - poor health, work obligations away from home, perhaps a family issue - the owners of some planes can't decide to let them go but can't fly them. And once flying currency is lost, it's a double challenge for the owner to return and get back in the air. So the plane languishes, one or more cylinders corroding, the corrosive qualities in the used oil doing its work, perhaps mold getting a foothold, and let's hope birds can't get into the hangar. Also consider: What are the chances a needed repair or compliance obligation is taken care of while the plane sits as an orphan? (A total non-starter would be a fabric airframe tied down out on a ramp).
Now consider what it will take to get that plane across 3000 km of sky, safely and without undue anxiety on your part or that of a hired pilot? There are probably two answers to that Q: It will take a fair bit of mechanical attention by someone who knows the model well, and it will take a fair bit of time. I have to wonder if you shouldn't consider a 'shopping trip' to a more populated region in NSW or Victoria where there's a relatively larger fleet of active a/c from which to shop.
Good luck on your hunt, no matter what you decide.
Jack
Prescott AZ USA