There are not a lot of things out there for this. The main thing in the rear is you can put fully adjustable control arms by using heim joints. This stiffens the rear end up and provides adjustability. The front you could also replace the control arm bushings with custom solid urethane or delrin bushings depending on what you are looking for. Then springs and shocks are about it. Almost everything needs to be custom made. I did this for my w124 coupe. I have solid rear subframe mounts and some of the rear suspension bushings and sway bar bushings are solid delrin. Got rid of a lot of play.
Are you looking for track use?