I want to raise the rear spring height for my 68 Chevelle SS about 1 inch. Does anyone know what springs would interchange to give me some lift? Just want to clear the tire opening with some wider tires. Used to have an older Moog catalog with all the specs.....but can't find it.

CC507's will give you a good lift.

Do a search in this forum for CC507, and you should find at least one members pic with them.

You could put in a set of air bags for about the same price. This will give you adjustability and usually better traction.