73 360 Ignition timing after Chain replacement

You should have degreed the camshaft. End of story. Now you don't know where anything is.

The gear set I used only had 3 settings. I am 100% Confident I used the stock keyway notch and corresponding markings.

When I took this engine apart it had a stock Chrysler plastic coated gear set on it, with no adjustments. So there was really no reason to assume the cam was meant to use with anything other than stock markings.