Big Block 454 Timing Question?

[savatreatabvr]

I checked the timing on my mid 70's C20 454 and the timing mark is way advanced to the point where it's almost not visible. The distributor is turned so far counter clockwise it comes close to hitting the intake manifold. The 454's runs best set at position, does that mean my timing chain has skipped a tooth or is it just worn out? If it has skipped a tooth can I pull the distributor and turn it back one gear tooth?