What I suggest you do is just buy another drivers side spring and put it in place of the passenger side. Or if you want it higher get the passenger side and swap out the drivers.
if you still don't like the ride height flip the front bracket.
I would not suggest using the same spring on both sides. the right rear must be stiffer than the left to accomodate the torque of the launch. In some cases cars have been known to "jump" a full lane to the right on a hard launch without proper spring rates. You have to accomodate for the higher torque going to the right rear due to the rotation of the drivetrain.