Do you have super stock springs? they cause the passenger side to sit a little higher due to the extra leaf on that side. You said you springs had been changed. Maybe you have ss leafs?
Finally... I waited to see how long it would take before someone mentioned that. ( extra spring on the right side) See if you can find some numbers on the springs. Both sides because they will have different part numbers.
Mount the battery on the right side always the weight of the battery will lower it maybe enough to level it out. The battery on the right side is better for traction verus left side.