He may be right about that. Chrysler did that with their early Hemi truck heads. I have a set on my 56 331 Hemi on the stand in my shop. They also did it on some of the big block heads on medium duty trucks. It wouldn't surprise me one bit to see some 318 heads with the exhaust cross over re-cast as a water cross over.
Especially in Australia. They got all kinds of interesting twists on American parts. The Australian Ford 351 Cleveland is a fine example of that.