Will you be using the car for road use as well? If you can stretch to it, I'd keep the cossie and get a dedicated track weapon. One of my good friends does a lot of track days in his Westfield, I've been out with him and the added fun of being out in the elements and cornering speed is unreal, can carry far more speed in to the corners than the 500+ bhp jap stuff.
I'm having a conundrum as to if I should part with my saff to free up some cash for my new car that I've ordered but I'm going to do everything I can to try and keep it as well, as folk have said, good ones are getting harder and harder to find..