Coil over spring rates

[Perry Mitchell]

I have coilover shocks on all four corners of my 67 Camaro. I think that the shocks need a different spring rate as they are very stiff. I wanted to raise the car 1 inch in the rear, but turning the adjusters up, the spring seems to get in a bind, yet, the car does not raise. Springs that are on the car now are a variable rate style with a rating of 175/350. There are two batteries and a large, heavy fuel cell in the trunk. Any suggestions?