No large flywheel is necessary...You can make a small hub, 2 inches or so, with the tapered bore and hold it on with the 8mm nut..Embed the magnet for the ignition in the bottom or side and make a bracket for the sensor, set for 28 BTDC..Then you bolt a prop hub onto this with 2 or 3 or 4 Allen bolts..the small hub can be 6061 aluminum, but for the other hub with the prop bolt in it, 2024 aluminum is stronger and will last longer....