Looking into upgrading rear suspension

I'm open to ideas on what I should do. I have an 8-1/4 attached to the stock /6 rear suspension. My car has a 340 with approximatly 350hp. Followed the Mopar Muscle magazine 400hp xe268 build up. The car is an auto with a TA tight 10" and has 4.10 gears and sure-grip. I think I have 318 tosion bars up front. I'm looking into raising the rear just a little bit. I had some tire rub out back with 295s on 15x8 wheels with 3-3/8 backspace. We used the grinder on the inside of the wheel lip.

The car is mostly a street car but I would like to take it to the strip and have fun with it. Should I look at the Super Stock springs probably the 3300 lbs ones? Or espo? I'm looking for something that will help with performance over the stock ones.

Also does anyone have pics from the side of a car with the SS springs. I'd like to see a side view and see how the car looks.

Thanks for the help.