Firstly hi and welcome to TorqueCars rex16v, nice to have you along.
An ex race car can be a good investment as they have premium parts fitted. Here are the pros and cons as I see it.
For a track car
It has been setup already. It is tried and tested and you will get the car with performance
mods for a knock down price.
Against a track car
It will have had a hard life and may well be in need of some major mechanical work.
For a DIY track car
You get the car setup exactly how you want. It will be essentially new and unstressed so will potentially be more reliable.
Against a DIY track car
It costs a lot of money and it tends to be a trial and error setup. It can take a lot of work to arrive at the setup you need.
Because you posted a link and had less than 10 posts your post was held up in the moderation queue. I have approved it for you now