yeh the reciept should be fine, should have his full name, address and license number...
Worked for me, although the car wasn't from another state
ditto
Actually for me the car's rego had expired but it had been expired for less than 3 months so I didn't need a blue slip. To prove the car was mine I had the rego slip (the blue piece of paper with the rego sticker on it) and took that to the RTA. You're meant to keep it when you have a car. The top half the seller keeps and sends it into the RTA and the bottom half you sign and show the RTA and they match it up and it's all gravy.