LOL guys! And welcome!
I agree with Josh, given the year, probably a JG, although could be a JB or JA if a retrofit boat (Could very well be if Berks are as rare as you say there in the land of Roos and Wallabes).
Steering IS on the wrong side for us Yanks not running whackers, but I have looked at more than one jet here in the Southwest US with right side drive. In front of the clean-out hand hole cover should be the oval label Josh referred to. Wouldn't be unusual for it to be missing either, but it will tell you the model, original impeller, and serial number. Year would come from the serial, but unimportant, really. Yes, they are ALWAYS in the center (Unless sumpin REALLY screwy like the couple twin jets I've seen).

I can't say much about the Dizzy any more though. I get to deal with it from both ends these days, so best to keep my mouth shut! They feel the same to me. (No, that is NOT a siggy line, but it DOES read like one, now that I re read it, LOL! I guess feel free! Teach me to come home and drink 2 beers in succession before posting!).
I am interested in just HOW those exhausts are hooked up and how they work THAT low on the transom. Never seen that before on a Jet Boat. More pics! More Pics! Looks like a VERY interesting Dingy you got there mate! I think we're all gonna be interested in seeing what you do with this thing if you buy it! (And YES! wanna see wildlife and scenery!)
Ray
PS, also either appears trailer either does NOT fit the boat, or the boat is nowhere near forward enough on it. This will cause some hook in the bottom over long periods. Just food for thought