Laurie, I meant to say it is a HX one gutted out at the top.
I pinched this image off Gumtree, 3rd from the left is a HZ 5.0L. As far as I am aware, most of the A9X's have the engine code in box 62 for the HZ style engine on their broadcast sheets. The only one I have ever seen with the earlier code on its broadcast sheet is the red hatchback H591125. I might be wrong in that there might be more with the earlier engine.
It was at this transition that the 5.0L engine changed dizzy and carby codes as well.
The HZ manual engine code is ZC. I think HX 5.0L manual is NT. I'm not certain what LX have in those boxes. I'm pretty sure in one of the press test images from 1977 of possibly the white sedan you can see the code painted on the rocker cover.
HZ intake.jpg 109.07K