[boxhead]

Your biggest problem with building a car will be when it comes time to pass the adr regs to recieve a vin number

From what I have been able to read and find out in regards to these vehicles is that most states within Australia you are required to register the car as a new vehicle and in doing so you must achieve all the current adr's for the year in which you attempt to gain a vin number.

So in doing so your car will need to be either fuel injected or running on LPG to pass emissions tests.

Most of the overseas manufacturers chassis would not pass the Australian torsional and beaming tests ie: chassis twist and flex.
Also not sure if the vehicles would pass side impact tests.

Apart from G Force I have not heard of another Aussie manufacturer with an alloy body.

As PCC said the little aluminium pieces on the leading edge of the rear guards are simply rock guards to prevent stones and gravel that come from the front wheels chipping the paint, I have seen some cars with clear contact applied there to prevent the same thing.
I think some of the originals had guards made from aluminium and some had the same made from leather (not 100% sure though).

Good luck with the search and dont be affraid to ask questions.

In regards to wanting an alloy engine over 7 litres from what I know your only choice will be a stroked gen III and at this stage to achieve that you will need to spend most of your budget on the motor.
There are some Aussie companys working on stroker cranks with only 1 available at this stage.