i put new stock height springs on my 70 Malibu. Im having problems with my inner trimmed fenderwells barely hitting the tires on heavy bumps. I replaced the 10 year old shocks with air shocks and pumped them up about 10-15 pounds to keep the rear suspension stiff and high enough so it wont hit the tires.Will gas shocks raise the rear height any or make it stiff enough so it wont hit the tires? Is there anything I can put between the coils in the springs to make them stiffer?