coil over shock question

regardless of spring length, Qa1 recommends the spring collapse 25%-33% at installed height.

For your 10" spring , that would mean the spring should be collapsing anywhere from approx 6-3/4" or 33% to 7-1/2" or 25% installed with the car at your desired ride height. On a drag car, the lighter spring (one that would collapse to 6-3/4") at your desired ride height) is often preferred because of the stored energy, similar to the stored energy of a wound up 6 cyl torsion bar.

if your 10" spring is collapsing to 6" to get your car to your desired ride height.....it is too soft.
if your 10" spring is collapsing to 9" to get your car to the desired ride height.....it is too stiff.

make sure the suspension goes up/down smoothly with little resistance without the shock....BEFORE the shock is installed.

On a street car where a level ride height is desired, I rarely find the two pre-load adjusters set the same. Usually the passenger side is wound further up due to the offset weight of the offset (approx 1-1/4") drive line.

you did not mention if you have double / separate adjustable rebound and compression shocks.....and where you have the settings selected to.