anyone got any 13" rims they dont want, prefferably in melbourne, 13 X 5.5" or 6" would be good, will pay for them

This is the size of 1960's Falcon and Mustang wheels (four-bolt wheels from six-cylinder models). Chevrolet Corvair wheels also fit the 1200, though Corvairs probably weren't sold in Australia.

Opal wheels also fit the 1200. I had to drill new holes to make Ford Mustang wheels fit a 1200. Here in the USA, Ford wheels do not fit 1200 hubs. GM 4-lug wheels do fit though.

Mareo

Mustang wheels 1974 and newer do not fit, yes it's true.

But in the 1960's, the six-cylinder Mustangs had 4-bolt wheel with 4-1/2 inch bolt center -- that fits: RWD Toyota and Datsun.

Which Opal did you use? In the US we had the German Opal until about 1974, when Isuzus were imported by GM and called Opals. I'm sure the wheels are very different between the two.

I had a 71 Buick Opal GT made by GM Germany, the mini Vette type body with 1.9 engine. It handled and ran very well but it wasn't very reliable. There was always something going wrong with it, especially the Weber carb and electrics.

I wish that I still had the14" aluminum wheels that were on it.

Mareo

Now there's a car I always wanted to put a 13b rotary in. I had also thought about a Cosworth Vega engine. Of course that was back in the day when I had a Cosworth Vega and a spare engine. Talk about cars that are hard to shop for!

So let me get this straight, 73 and older mustang wheels will fit my 73 coupe? Are those 13 or 14 inch wheels?

Yes, older Falcon/Mustang -- 4-bolt wheels. I think they stopped making them in '69 or '70.

I'm pretty sure these were only 13" wheels. The bigger wheels were 5-lug wheels for V8s and newer/bigger sixes (models with a bigger differential).

Two Cosworth engines? I know this is off topic, but was the engine really cool, or did it just look extremely good? That was the high point of the Vega line!

And an Opal GT -- I think everyone always desired one of those, even if just for a short time.

Datsun fans have pretty good taste.

Yes, it is off topic, but I'll reply anyway.
The Cosworth engine was really cool. They used to advertise it as "a car ten years ahead of its time." With an all aluminum, dual overhead cam, 16 valve, fuel injected four cylinder with a factory stainless steel tri-y hearder in 1975 they weren't too far off. The only thing that could touch it in the 40-90 mph acceleration was the Corvette.
Of course they also advertised it as "one Vega for the price of two."
Damn, now I'm starting to miss that car.