07. MSD offers their Pro-Billet line of distributors for all popular Mopar applications, including the low-deck big-block. We’ve had great luck with MSD distributors, and the Pro-Billet unit comes with all of the necessary springs and bushings for a variety of ignition timing curves. MSD shows the different timing graphs right on the side of the distributor box as well as in the instructions. Each application is different, of course, but for our big-block we chose the black bushing combined with two blue (light) springs for a timing curve that advances quickly to 18-degrees of advance above the initial timing setting.