Matt
Have you been following all the changes that are coming for modified vehicles up here? (I assume you are intending to get this registered?)
There are still heaps of questions to be answered by the "powers that be" but 6 point cages (and door intrusion bars) are off the menu for new cars under the new scheme.
I dont know if you could get a mod plate done and then rego it later but it might be worth speaking to someone local that does the blue plates now?
I think there is a link to actual copies of the new rules on the Brindabella Motorsport forum?
Cheers
Shaun B