Thanks Joe & Andre.
The rear wheels appear to be cast with a domed shaped grease cap which would not be present at the rear hubs so I drilled it out.
Opened the torsion bar access in the rear fender just ahead of the rear wheels – Porsche race cars almost never have these covers in place
Subtly re-shaped the rear wheel opening - thought they were too flat at the top
Working on the tires to soften the square edge of the tread surface and knock down the sheen
Before: