rear end alingment?

ok I bought new springs and installed them with new shackles and and all new bushings but I measured and one side is moved foward 1/4 inch to the front so after measuring from the cross member to the spring mounts one side measured 57 7/8 inches and the other measures 53 1/8 inches so i measures from the center of the axle to the rear of the LCA still 1/4 off i measured from the back of the LCA to the back of the cross member and I think it measured 16 inches I guess the question here is can I put in a spacer in between the mount and the perch to compensate for this?

thanks shiifty