69 dart sags in the rear

I am currently using helper springs to lift the rear. I have been doing some research but I cant find any pics of cars with jacked up rears. I live in the middle of nowhere so gravel roads are an everyday thing. The front of the car has to sit higher than normal so I dont bottom out the headers. What is a good spring to run that raises the rear but doesnt loose its arch (mopar super stockers) in a year.