GF has a 2010 LT2. She doesn't want it lowered just leveled. only pic I have really of her car.
Question is I have a full set of stock 07 SS springs, if I was to put the back spring on from my SS-SC would it lower the back to be more level? Sorry I'm not looking through 100s of pages of suspension questions to see if this answer might be in there so sue me.

 

SS springs do sit lower so it should lower the back enough to look fairly level, but they are also stiffer so it may feel strange to drive having a stiffer suspension in the rear than in the front

 

so is there a spring or shock I could use thats about the same stiffness? I know the rear koni's are adjustable but still believe id have to get a different set of rear springs.

 

Just try it and see how it feels. The rear springs on these cars are stiff then the front anyways

 

Eibach Pro Kit. It will lower it about as much as your SS/SC sits stock and it would level out the back with an even spring rate all around.