Points of difference for X-flows were gearboxes, bellhousings, distributor, carbs. Auto gearboxes were early 70's AMC 343/304 spec. Distributor was based around a Chrysler/Dodge truck item, carbs were Fiat/Chrysler Centura C 180/C200. So there are parts around for Falcon X-flows from other models.
All the rebuild components should be able to be sent to you by a willing helper from Australia or New Zealand. The parts are still around in the aftermarket for 2-bbl Weber equiped engines.
For the X-flow distributor, they still have parts ex Bosch for any Aussie Duraspark (branded Motorcraft, and with an integrated spark controll unit)
For the 1982-1987 carb rebuild on US soil, I think you could use the stock ADM 34 rebuild kit sold for US market Fiat X1/9 and Fiat 131/132 (1978-1980). These ran a similar ADM32 carb. The earlier 1-bbl carb found from 1980 to 1982 was a local Stromberg carb specific to Australia, and is something of an orphan, but it follows on from years of Chrylser/Dodge/Holden 1-bbl Stromberg carbs made from 1952 to 1981.
All 1982 to 1991 carb 3.3/4.1 X-flows have a return line Weber 2-BBL carb which is reliable and simple. It follows Mustang 4-bbl logic, with a cold fuel return line. The Falcon carb is Fiat 131/132 X1/9 based, and is integrated into the stock emissions system found in the Gregories # 226 workshop book. Really simple to sort.
If you'd like to run a more US friendly system, then I'd look at any 2-bbl Holley 2300, Holley Weber 5200 or Autolite 2100 or Motorcraft 2150. Problem is the new carb has to fit the confines of the existing 2-bbl or 1-bbl manifold. Additionally, if you use the stock automatic gearbox, a Borg Warner kickdown linkage is needed and an automatic choke.
If you want to use a US distributor items, just use the 1975-82 duraspark II from US 200/3.3 Ford I6 (or 75-80 US 250/4.1) with a 1974 Duraspark cap.
If you are still running a stock Borg Warner auto, an AMC 343/304 carb and kickdown fits the Aussie Borg Warner 35 or 40 or 42 transmission which came behind the Aussie x-flow. The 1968-1972 AMC ran the same gearbox, and a carb which fitted to an AMC would do okay for a Ford X-flow with this transmission.