As stated above it all really relies on your driving style. I personally don't ever run progressives on the rear. Never have liked them.
If I was running a 2.5-2.8 front spring, normally the rear will be a 2.6-2.7 linear spring. Front softer as a 2.3-2.6 spring (sounds like it would be a better option for you honestly), I'd run a 2.3-2.5 rear spring. Again, it all depends on your layout, driving style, and also positions of the shocks on the tower has a great effect on how it handles and drives.
In recent testing (thanks to a discussion via text with Robbie) I've learned and felt that the rear springs as a 2.6-2.7 rate in position 2 feel the same as a 2.5 in position 3 on the tower, with the exception that the 2.5's allow the front to gain more traction on corner entry.
In the end, it's all how you drive, and what you feel. Nothing will ever replace track time and learning every moment you can. Try things just to try them. And when track conditions change, go back and try the same thing again. See how it feels different, how things change, then take notes or lock that info away in your brain. It helps growth.