for everybody's information, in case they read this thread, the E150 springs on an a-body result in a very stiff rear end. We used the E150 spring with all of the leaf's, but we flipped over the short (stiffest) leaf. You do this with a couple (3-4) big c-clamps and a screw driver in the bolt hole. The spring center bolt does not end up in the axle bracket hole, but ends up behind the bracket. You then align the axle/spring on the car with a 25' long tape measure, locating each side of the axle to some common forward point on the car.
This spring setup results in a spring that is about 400-425# /inch rate. We put this on a road race course car, and it works great for us.
