Dave (I assume),
I don't believe there will be anything in the serial number that will indicate any of the features that you mention.
There are, however, ways to see if the different parts of the gun are serialized together and if they match within historical timelines.
As far as the poly-choke, the way most are determined factory original is if a) the barrel has no choke markings or designation on it either on the left side or on the bottom, and/or b) it is integral of the barrel, meaning shoulders of the start of the choke device are part of the barrel steel and there is no seam at that point.
Let me know if I can help you further.
Will