Spit & Polish in Tonbridge are the only place I've found to date who have a CNC lathe compatible with the Turbine profile. Many places have "upgraded" there machines since COVID and are incompatible with Classic Car wheel profiles
S&P can do a grey finish but it would be Wet paint, not powder coat. I'm hesitant about how durable this would be, particularly as it looks like they will charge an additional premium for a bespoke colour.
I'm considering therefore going Black, but then when I get them back, doing the wheel centre with a rattle can grey. There is so little of the outer turbine 'blades' seen, that I can live with them being black ( they'll be black with Brake dust anyway after a few hundred miles
Any considered wisdom in the forum if PPC is that much better for wheels ( or worse).
Tony