Strictly for judging dates are not looked at or considered for anything but unrestored or thoroughbred at MCA
Now just to get things original - our focus here
Your date of 6A2 would decode as Year, Month and Week so 1966 - November - 2nd week
Its believed that Holley may have built specific application in groups then moved to another since they were supplying allot of different car companies as well as their aftermarket business. Returning at a later date to make another group as needed. If this is so then we would expect that the spread between when the engine was built and when the carb was built could e a little greater than "normal" when compared to parts built on a regular basis by Ford plants.
I don't see a problem with this date and your cars production date. It might be better to compare the Nov 66 date to when your engine was assembled IMHO
Thinks like this will be covered in a new article covering how to read and decode part dates in the near future. We're working on it