Here is the thing, and why I would suggest not starting with the starter. I agree, its possible the distributor gear broke apart. In all the years and all the early 6 motors I have ever messed with in 42 years, I have never seen that happen. But no way would I ever say I have seen it all, lol. However, If the cam gear is a fiber gear, and if it did come apart, the cam will maintain the valves in whatever position they were in when the gear let loose. If any of the intake valves were open, using the starter to rotate the motor will cause the piston to come into contact with the intake valve instantly bending it. that may have already happened, but if not, no sense in causing any further damage. I would probably just pull the valve cover, then all the plugs, and then turn the motor over by hand at the fan, or at the flywheel with a flywheel turner. If the crank turns but the rocker arms are not moving then its the cam.
