Long and complicated ferry trips are fun and brutal at the same time.
It’s not the time in the air that will test you it’s the time on the ground. Get the biggest auxiliary tank(s) that’s certified for your aircraft. If you don’t end up capable of 400+NM legs then I’d check around to see what other options are available that can be certified for no passenger flight only. If maximum gross weight is an issue then request permission (No technical objection) from the OEM to fly above internal gross weights but within external gross weights for the ferry trip.
Use a handler for every stop outside of Oz. Don’t expect the handler’s bill to be big, expect it to be huge!
If you have limited experience on the route then bringing someone along with experience may help tremendously.
I’ve flown all of the countries between Oz and Pakistan, several in the Middle East and another dozen in west and South Africa. If you are in need of an expensive solution then PM me.
Cheers,
BB