I would be safe and go with what Exedy Aus is specifying. As you mentioned, the US had a different transmission, which means possibly a different size transmission housing. Normally, the number of gears don't matter, but the size does. E.g. K20 engines are meant to be only different in stroke and head, but their not. Even the clutch is different diameter.
If stickier tyres is all you got then OEM is fine. As I said, only if you had done all those engine mods + the tyres and a lot of race starts, then I would grab the performance clutch, otherwise, I wouldn't bother.
I'm not sure about the labor charge. Last time I changed a clutch, I paid $100 for labor, however I'm friends with the mechanic (when I said friends, we're actual friends and not the type people usually talk about just knowing). I also helped out with the change over. I'm guessing labor alone should be ~$300-$500 depending on the amount of time needed. Very rough estimate though.
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