Finding Initial TDC on 79 SL
 

I am putting the engine parts back together from a box of parts. I have the vibration damper with the numbers / degrees offset on it. What do I line this up with? Is there a mark on the block or timing cover that I am missing? I know the TDC sensor lines up with the notch in the damper once all is together, but what do I initially line the TDC mark up with when I am putting the timing chain on?

Thanks in advance,

Shelby