http://www.infrastructure.gov.au/roads/vehicle_regulation/bulletin/pdf/NCOP3_Section_LA_Engine_01jan2011_v3.pdf
That should cover most of the stuff you need to know, main thing for conversions is on page 11, it explains the CC's to Kg ratios and all that. There were some changes done in Nov Lat year but I copuldnt find any updated documents regarding engine conversions so i'm guess they didn't change anything regarding conversions.