Ok here's my report, of sorts.
I decided to use the Ford GT Concept '02 and figured out that due to its 1451 Kg weight, my ideal power output would be 527HP, fortunately fitting a PC chip & Semi Race exhaust got me to exactly that figure.
I then bought all the allowable parts including the mandatory S1 tyres and Sports Suspension kit.
I've used this car for a
top gear comp a while back and my memory of the car was that it was quick and also drove well. First time on track proved otherwise, It seems the car prefers the stock S2 tyres, as with the S1's it had lots of corner entry over-steer, it was controllable once on the throttle, but braking and corner entry was pretty unstable especially considering I was going to do a 21 lap race.
So I raised the front ride height and lowered the rear, softened the rear dampers, and then added more rear camber than I did for the front. I also wound the brakes bias way to the front, and added about 10points to all the LSD settings. The car was now controllable, but it still required precise braking and steering entering the chicane, hairpin and the esses at the end of the lap.
I was happy enough with my race consistency, only losing it once majorly (getting wide through the last corner and spinning, which cost me about 10 seconds), and I had a few other less significant moments as well, meaning a mistake free run would prob be about 15 seconds quicker.
So it was A very challenging race, as keeping the rear end under control for 21 laps was pretty tough, it was still easy to drop time or lose it in pretty much every corner, but that's what made the race more rewarding I guess.