ask how many kms the 6m-ge has on it (as it's an engine conversion)
if it is in good nick, 4500 is about what you'll pay. blue slip is a minor issue usually.
if it's in sydney, I could help you out and take a look at it for you, check for rust in all the usual spots, tell-tale signs of accident repairs, etc
edit: except yu're not in syd
edit2: except you are