hey mate, '15 370Z in Victoria here. I just ordered all the front and rear parts needed for the Nismo conversion aswell as the under tray from a dealer down here. Didnt need to ask about VIN or anything, took a long time to get all the parts (Ordered in mid Jan and the final part came today) Guy was super chill and super friendly. Just gave him a list of parts I wanted, explained what im doing and it was all set. I did have the same thing happen from one of the dealers but they were a specific Nissan "Nismo" dealer.
If you need any help just PM me