Looking for a little advice on the timing numbers I just pulled from my 73’ Duster (backfire issue)

Small changes in timing wouldn't effect it (exhaust) so directly or obviously.
Too much timing will cause a gurgling or pinging sound under load. Under heavy load (full throttle) this is real bad and need to get out of the throttle immediately. You can look at the spark plug porcelain for bits of aluminum - that would be sign of detonation under load.

Too advanced for the conditions can contribute to excess NOx which is sort of brownish. I just think that's unlikely. It would ping or at light throttle, trailer hitch (feel like the car is getting jerked ).

What color is the exhaust smoke and under what situations do you notice it? White? Brownish? blackish? bluish?