Cutting coil springs for street use is for losers, & if i remember rightly, it's illegal over here.
You should be able to get some real stiff springs & make it rocket round those bends like nothing else, but you would not want to live with it on anything but a dead smooth road.

If you follow the advice offered up by tsillay & 1200rallycar, you will be right on track, but get new [or used] springs that have been made for the job.
I liike Koni shocks myself. You will find that, if they are still available, they should not be too outragously priced, & if you get the adjustable ones, you can fine tune your suspension to suit your style, or the type of motoring that you will be doing on any particular day.
You know, set them soft to pleasure the little woman on a Friday night, then set them stiff for that hot lap down, or up, Mulholland in LA[?] early sunday morning.