The Aussie 302C head is a 2V head, the exhaust ports are significantly smaller than those of a 4V head. The Aussie 302C head has more flat "flange" around the exhaust port than that of the US 2V head, and 4V exhausts can mate & seal on the Aussie heads. The US 2V heads do not have as much mating surface, and the ability for a 4V exhaust to seal is "iffy".
I agree with Dan, the best way to go would be to run 2V headers designed for the Pantera.
Your friend on the DTBB, George