Wake up a 1968 318...

But remove the distributor cap first so you can watch the rotor.

If the crank turns without immediate rotor movement, the timing chain is worn.

Rotate the crank until the rotor moves, then rotate the crank in the opposite direction. If there is a lack of movement in the rotor, bad timing chain.
Sounds good.

Unfortunately I now have some more issues to deal with because I started leaking coolant from the back of the motor. I am pretty sure that their is a bad freeze plug or plugs back there, but it's behind the transmission so I am not sure. The rest of the freeze plugs on the motor are all shiny new, so I am hoping that that is all that it is.