Australian Design Rule ADR 27 in 1973 was = US 1968
Australian Design Rule ADR 27A in 1976 was = US 1973
:arrow: Australian Design Rule ADR 37A in 1986 was = US 1975
All post January 1986 Falcon cross-flows, 3.3, 4.1, or 4.1 EFI, pass US 1975 unleaded, cat emissions standards. For post US 1980 compliance, check if just the visual inspection is enough. The compliant 2.3 liter US Holley Weber fits the carby 3.3 and 4.1 X-flows. In Aussie, they use Fiat/Chrysler C180 based Weber ADM carbs in the stock set-up. So if it has just EGR and no air pump requirement for the year, you may get it. But some emissions guys also activate the year of engine build legislation.
Some authorities allow a baseline certification. You grab a complying 80 000 mile car, and test the emissions stock verses with the modification.
As Jack says, it
depends on the requirements of your locality. In some places it would never pass the visual. In others, it only has to pass a sniffer. In still others, it wouldn;t get checked at all.
Talk to the EPA, and get clear on it. Then check with the nastiest guy on the block who does anual inspections.