This was great fun. Used the Single Player mode (Arcade Mode in early GT games) and did a Single Race of 5 laps. Used the Greaves Motorsport P2 thing, tuned to 600pp on RH tyres. Huge fun.
Watched quite a few motorbike races around here. The elevation changes you've achieved are impressive. You can't get them exactly right in GT6, naturally, this does make the recognisable though.
Good use of scenery to mark the turns and make each one feel different. Could you use the thin metal gantry across the GT6 sector timing lines, even if that's less authentic?