Traction Issues

I have a 1970 Swinger with mild 340, 4 speed and 3.90 posi. It has super stock springs, drag shocks, pinion snubber set at 1/4 inch, Hoosier Quick Time Pro tires and 310 rear wheel hp. I raced at Rock Falls WI yesterday and could not get traction no matter how heated the tires or what RPM I launched at. The track was supposed to be prepped but I still managed to spin through most of first gear and part of second. Ran a best of 12.93 @ 109.3 mph with a 2.0 60 foot. Any help would be appreciated.