The dash is shown in 2 brochures in HJ that I'm aware of. The Oct 74 one (with the red van and yellow ute at the dunes) and the Feb 76 one (Son of the Beach). Both feature silver dashes and the middle vents. That's not to say the images for the brochures weren't lifted from a HJ GTS file.
Point is if I was restoring one in the last 40 years I might have used that as a reference point and gone silver.