It has been my experience that the best way to obtain the correct information is to ask those with the authority in the area. Phone the RTA and ask. As of February 2006 all States are adopting the National Code of Practice: Light Vehicles VSB 14 - see DOTARS web site. To my knowledge NSW is not yet onboard but intends to do so shortly.
As I understand it, all new certifications now should comply with this Code, so you may not be able to roll-over your Vic certification unless it's at VSB 14 standard. Also the States only accept certification from the engineers on each State's register.
Again I recommend you get it from the horse's mouth. It's also a good idea to shop around for quotes from the engineers. Many are making good money from heavy vehicles and aren't interested in touching light vehicles, so it can be difficult to get them to even provide a quotation or if they do it can be way over the top.
Hope this helps.
PS. Always consult with the engineer BEFORE you do the mods, it can save you time and money.