stock i suppose, i think the 4cyl springs will make it handle a little worse on those fast corners, i might be in the same boat as you, i can't find any stock ride height stiffer springs, all i've seen is lowered..if i lower my car the front end will scrape more often than i'd like(which is never)..but for drag/street where you dont do many high speed turns i dont see why you couldent run the 4cyl rears, if i understand right you want the car to look like it's launching whihc it's stopped, which means the rear of the car should slightly lower than the front for it to be ideal, if you want grip i'd start with new tires, you'd be amazed at what a quality tire can do(i just replaced mine, 80.00 a tire was worth it)
~Mark~