Springs and struts/shocks are interchangeable. GT springs have a higher spring rate, shocks are calibrated differently. Sedan and wagon have slightly different rear springs.
Unless you are getting them really cheap, think about getting upgraded shocks at least. IMHO, the stock GT shocks are not matched all that well to the springs. Your car can handle pretty well with stock GT springs, upgraded rear sway bar, and Koni Sport or Bilstein HD shocks.