You can use 12" springs for the front. But I agree with GN. 250 is too high if you're looking for all out drag perforance. Depending on the nose weight I'd try 175's. Then if it doesn't coil bind you can try 150's. Used springs are only 50$ or so, so its a cheap investment that you can turnaround and sell if you can't use them.

If I were you I'd put those LCA's on the upper bolt then get some UCA's that relocate the rear pivot point. Set your ride height and pinon angle and test it. If she spins then lower the bolt on the LCA's to increase your AS. You don't want your AS too high. Between 100-110% is optimal.

-Mark