The one's that are usually used are P3412002/P3412003, or the "002/003" springs as most people call them. They're recommended for a 3200lb vehicle weight. Maybe a little on the heavy side if you've done much weight reduction on the car, but they seem to get used the most for most A-bodies in street trim.
http://www.summitracing.com/parts/dcc-3412002/overview/
http://www.summitracing.com/parts/dcc-3412003/overview/