I don't know if NASA has races in your area, or if you want to tow to California, but they have a class called CMC (Camaro/Mustang Challenge) that allows minimal modifications. At least compared to most SCCA classes. It seems to be growing well in north and south California as well as Texas and I believe on the east coast. Very racer friendly overall.
Whatever you do, read the rules of the organization you intend to run with before you start on the car. They differ widely on things like cages, suspsnsion, engine. If you are very careful you can have a car legal for more than one group, though not likely optimal for either.
Spend your money on driving schools and a good cage before you worry too much about engine/suspension mods.
When you get to suspension, I've been very happy with Maximum Motorsports torque arm and other pieces on my auto-cross car. Others swear by Griggs. Evolution has a bolt-in 3-link set up that seems to be well made and several people have them now. Finally, don't overlook Steeda's 5-link. It seems to be popular with some successful road racers.
Mustang - The Great American Kit Car
#50 ESP/SM2 (backup) - Cal Club
Porsche - The Great German Kit Car - #50 SM2 Cal Club - #84 JP PCA