I used an ATI damper with a 3 bolt Chevy pattern. Used an MSD Small Block Chevy crank trigger kit. 3 bolts with 4 magnets gives you some clocking options. Set the engine up at 35* BTC, picked a clock location and built a bracket to mount the MSD bracket and pickup in the center of the adjustment window with the pick up in the correct location at a magnet. Simple. Worked perfectly.