I have the Whistler Mustang in my stash, so I'll be very interested to see how you progress and what you find.
One of the things I keep going back to is building Triumph road cars, for the models that are available in plastic at least. Now, the Triumph TR-8 cam with Tartan seat covers. I haven't even tried tartan when I'm painting figures. If you could please give some more details of your technique, I might be able to utilise the same.
As far as my Porsche 962C goes, I had a model club meeting last night so all I've done is attach the Studio etched seat belt to the seat, after priming and painting it flat red, and adding some brand decals from the the spare decals folder.
Tonight I hope to finish the headlight assembly, mask and spray the edges of the windscreen and windows, and if I'm going really well mask and spray the cockpit back and floor assembly.
Once all of this is done, it's final assembly time.
Cheers
Tony