Just using the knowledge that I've been compiling over the years of being a car-addict, Z-cars very much included. Hopefully soon, I will be racing cars often.
For springs, JohnC recommends using 280Z Tokico springs as they are linear rate and can be cut to size. Keep in mind that when you cut springs, you are increasing their rate.
FWIW, I remember at least one person here posting a video of the suspension moving during a track day. Just found it, brought to you by clarkspeed: http://forums.hybridz.org/index.php/topic/97034-video-of-working-suspension/
I think it's great that you're getting your kids involved! Not enough people have any sort of mechanical aptitude (let alone aptitude of any kind) anymore.