The I&T service manual shows a layout of the three gears: 1)crankshaft, 2)camshaft & 3) combo governor/mag/dist drive. The crank gear should have a straight line mark on one tooth on the flat face of the gear. The camshaft gear should have a corresponding straight line mark in a valley between two teeth on the keyway part of the circumference in line with the keyway. This mark is also on the flat face of the gear. These two gears should be mated so that the two straight line marks are aligned with each other.
On the circumference opposite the straight line mark on the cam gear (and opposite the keyway) there should be a dot or an "o" mark on a tooth. This mark is also on the flat face of the gear. It should be aligned with a corresponding dot or "o" mark located between two teeth on the flat face of the combo gear.
The marks are small and may be difficult to see but should be there.
Hope this helps.