Go with the 0.920, unless you are trying to transfer weight while launching at the track. They will not be too stiff. These cars were set up with soft suspension back in the day. I ran 0.920's on the street for ten years and they seemed soft. I upgraded to 1.06's for better handling. The back end has two left SS springs and it rides fine on the street. Still manage mid 12's at the track.
