Old Truck, Modern Engine

I believe that's the rule in South Australia. In Victoria there's VSB (Vehicle Standards Bulletin) 8 and VSB 14 that cars /utes/ panel vans need to comply with. Motorbikes, trucks, busses etc are not explicitly stated for but are implied to comply in spirit. Part of the reason is a truck may have had 2, 3 or 4 different brands of motors fitted before it gets restored. Basically now if it needs and engineers certificate and is post 49 it will have M plates. However these are only 4 or 5 years old so vehicles older than that went on CH or H plates. VicRoads will deal with them as the police bring them up or when the vehicle is sold as those plates are not transferable.
There are a lot of lowered cars with their 13 and 14 inch rims replaced by 20's. Not my cup of tea but I don't mind a period looking alloy wheel on them either

That s like a guy I knew had the worlds rustiest FJ 45 ute....evry weekend on the beach......anyway the cops stopped him ,and sent him for a machinery ...which it failed ............not a problem ,he had a RWC licence ,and wrote out a RWC , surrendered the old plates and re registered the truck on one visit to the TMR customer centre.............all on the same day.