It wasn't a bad question Jon, and you're not the first guy to confuse the terms C302 and 302C. You knew what you had, that's whats important.
It sounds like you found some posts/threads that explain the flange around the 302C exhaust port is large enough to seal a 4V header? That's why the 4V headers will work with your Australian heads.
Happy Holidays!
-G
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