Since you seem to have mastered this car, here is a question I've had for some time. Did you ever get the car body to stop oscillating when you go over 200 mph?
I've mostly B-Spec'ed this car in the past.
I've lost 2 HP permenantly on this particular car from crashes, so I'm probably going to have to replace it. Narrow tracks and high speeds are not a good recipie for me and long car life.
Yes, the way I have this car setup, there is very little wander at high speeds. Although with all the aids off, I do get a little squawking of the rear tires between 190-250 MPH. The really high powered MR cars, require really good/precise throttle control when changing direction, only full throttle when the car has no steering input, or it will wander and oscillate.
We setup cars completely different, but mine is setup again with a loose suspension specially in the rear (spring rate 12ish & 6ish), and very little bound and rebound (front 3 & 4, rear 1 & 2). Ride height is 5-8mm higher than minimum in the front, and 20mm higher (than the front) in the rear, to push more weight up to front for steering at low speed/deceleration. As far as Camber, I reduce it the front to around 0.8-1.3, and eliminate camber completely in the rear, I also add toe in on the rear for straight-line ability only one or two inward makes a big difference. Stabilizers are almost eliminated, going 1 & 2. Gears, I setup 1st to be real wide, 2nd & 3rd are mid range, 4th, 5th, & 6th are increasingly narrower than the previous gear, and I keep tweaking by .005 until all the shift points are right where I want them. All aids are off, as they only sap power, and make the car more unpredictable, and malfunction when your line is off a bit or bump a rumble strip. Downforce I drop slightly in the front only about 2-5, and drop the rear to within 10-15 of the front. LSD is key depending on your driving style, mine is setup to limit Initial Torque at between 25-35, Acceleration is a bit higher at 40-50, and deceleration is high too between 40-50. I haven't fine tuned this enough yet to even play with ballast. Oh I almost forgot brakes, even though I rarely use them on this car, when I do they need to be extreme, my settings are quite high in the rear 18-20 (also why the LSD in decel is high), and the front is much lower at 5-10, I like the 3:1 braking ratio (rear to front), so the rear end breaks-outward improving my acceleration line.
Hopefully I have explained my setup adequately, but it is from memory as the PS2 is again packed up, as this week & weekend I'm finally moving, for sure this time as I already have keys, and am starting to move boxes once I get a few cups of coffee in me. When the move is complete and the internet is up and running at the new place, I can give you more exact numbers rather than just ranges from memory.
I do love the insanity of the car & track combination, very fast, and exacting, if you make a mistake you know it, as you either spin-out or hit a wall then spin-out. The occasional wall taps are almost unavoidable at these speeds, and with this combo I don't discount a time for a quick wall rub/tap on the rear quarter of the car, but for a hard hit against a wall I don't count the lap time. I think my 1'09.9xx was completely clean, but a two of the 1'11's had a slight bump at turn 9, which is my issue here, Turn 9 and 10 I have the tendency to come-in too fast, and kill my lap.
Good luck.