I hope you know that when you use one of the optional crankshaft sprocket advance-retard slots, you must align a different mark (triangle or square, instead of dot) with the matching mark on the camshaft sprocket. That Cloyes S-338 sprocket has just the single dot (for "straight-up" timing). It is really just a tooth number you must get correct on the cam sprocket, but without the mark as a guide, one could make a major mistake (crash valves into pistons). Of course, if smart and you use a timing wheel, you can probably assuredly set valve advance or retard.