Thanks guys, you are all legends.
Turns out my car was manufactured in Dec 1973 and first registered as a 1974 model in USA.
I made my appointment this morning and the car is now fully certified and compliant with Australian Design Rules for the year of build. The Engineer was really pleased with the way I had set the car up, seatbelts, lighting, emmisions etc.
Now just to book a registration appointment this week and I'm on the road.
Thanks for all the help.