Yeah, if you put an aftermarket stereo in your LHD car, they won't register it in South Aus. I'm not making that up...
Having said that, on the subject of buying and registering a car, keep in mind that if you're looking at buying a 40 to 50 year old car, that it's a 40 to 50 year old car and not a 5 year old Commodore. Even if it appears to be 'restored', you still might have a couple of things to attend to for registration...