Thanks everyone for your feedback. The serial on this one is 27,325,662. I spoke to the shop and they are very understanding. Their master watchmaker seems quite certain the dial is original based on a number of factors, including the patina, the position and impression of the feet, etc. I am, however, still not certain. I have found a couple other examples of non transition dials in this reference, but they are a little weird. I’m posting another example from 1st dibs as a photo in this post. I also consulted a Speedmaster collector who believes as many here do it should be a transition dial. The shop would swap the Speedmaster for this 1966 Navitimer if I’d like to, and I’m considering that option:
https://fathertimeantiques.com/item.php?item_id=1626&start=0&criteria=^0^0^0^4