That's the story of everyone's life Even coilovers will leave you with a raked stance... Most lowering springs (for Volvos specifically) will leave the rear sitting high.
Elevate springs might bring your rear a tad lower.
I know many will hate for this, but I'd suggest just cutting a dead coil off the rear springs. It's not going to effect your handling to the point that you'll die, you'll probably not even notice a difference other than weight shifting further back with less rake.
If you look at the spring construction, those tightly wound coils literally sit on top of each other when the car is on the ground.
Cut off 1 or 2 coils (make sure you don't cut so far that the spring does not seat properly when jacked up), and you're just lowering the car by an addition 10mm (or however thick your coil is).
From a physics standpoint, you are altering the spring as a whole. But you're not really effecting the portion of the spring that is actually used.
Coilovers often have less coils than lowering springs. The difference is made up in adjustable cups that sit on the bottom of the spring. These are basically in place of those tight dead coils and allow you to adjust the spring up and down.
For any flamers that jump in... I'm not talking about cutting stock springs down to just 2 coils for a slammed ride. That is stupid.
I cut 2 coils off my Elevate lowering springs on my S40 and the ride was perfect. Yes, more stress on your rear shocks, but throwing in lower springs will add that same stress.