I put the duster on the drag strip

Check this out,Kiddo: Put the rear end of the car up on jack stands,on the frame rails. Take your jack,jack up the rear end slightly, 3-4" . Loosen a lower shock nut off,let the shock drop down.Slowly,let the jack pressure off. When the rear end droops completely,see if the lower shock eye matches it's mounting point,with the spring. If not(what I expect to see), grab a measurement with a tape measure(fully extended). I would expect your shocks,need a longer length. Why I mentioned,the Imperial shocks. A video ,of a launch,(strip/street) would be priceless.