From memory it involves changing the flywhights on the mechanical advance to suit your needs. I think lighter weights means the advance will come in later and slower but I am unsure. The dude should only need to know what ever mods you have done to your donk and most importantly what fuel you will be running on everyday. He will adjust the advance curve to match the fuel you are using. I dont know of anywhere in melbourne but I got my old 351 CLEVO dizzy done at SAMS PERFORMANCE in SYDNEY. Ring up an LPG conversion mob like GasResearch Aust and ask them where they get their dizzys done because when you convert a car to straight LPG it is highly reccomended to get the dizzy regraphed. Good Luck