The engine is 65.35 inches long, 35.67 inches wide and 52.56 inches tall. On the 3406, the bore is 137.2 mm or 5.4 inches and the stroke is 165.1 mm or 6.5 inches. The displacement, or volume of air moved during each revolution of the engine, is 14.6 liters or 893 cubic inches. so you could divide the the length of the block by 6 and use 5.4 inches as your scaling point to make your cylinders and the gap should be even