How hard are you going to be pushing the car and does it need to double as your daily driver? If you are looking for a autocross toy you might just want to look for a used Viper or something along those lines. If you want a new car for a daily driver that you can also autocross then that is different.

I recall that Tim and I had multiple conversations on the subject while wrenching on his Valiant. In end we decided that it would've been easier and cheaper to just buy a used Vette or Viper to go racing in. Turning a Valiant into a Viper beater is a lot harder than just buying a Viper.