The flywheel pictured is missing the outer ring..
FWIW. If you are very careful degreeing the cam wheel to the crank, you can use a mark on the cam wheel. You must use a good light and double check the advance to a very small variation on the mark. A degree off at the cam is two at the crank.
HTH, MM
Also, you can use a mirror on a stick, under all the crap, to get into the bell hole.