Turbo is less emissions if done right, such as that done by a team of engineers at GM. However, the engine timing and carburetor circuits needs very careful tuning to work correctly with a turbo. If that is done it should pass. Wasn't this car supposed to have been certified in another state already?
The emissions standards in most places are either the year of the car, or the year of the engine. So putting an A15 in may need to pass the 1979/1980 emission standards. For replacement engine (A12) the year does not matter, so putting a 1981 A12 in a 1971 1200 doesn't need to pass any special regulations.
NSW specifically regarding SAFETY
Quote:
Significant modifications requiring certification
* Fitting of turbochargers or superchargers not originally offered by the engine or vehicle manufacturer, or increasing the original power output by more than 20%.
NCOP makes a difference between turbos that make up to 20% more than a stock engine, and turbo installations that add more than 20%. It looks like the latter will need to meet a raft of regulations including newer ADRs that don't usually apply to 1971-1973 vehicle.
Talk to an engineer.