Clamping the front of the springs?

If I'm reading this correctly, although it sounds like more street/cruising use then the track, i'd still go with the SS springs vs the XHD's. That's a big powered car and I'd install them as is and get a feel for how they work with your combo before clamping...or unclamping anything at first.

This would really just be the tip of the iceberg as far as how it reacts. Bite/tires, Pinion angle, shocks, and experimentation will tell you what works as far as track use.