Tim, welcome to the group.
I wouldn’t worry to much about the fact that your car was registered as a 1970 model though manufactured in early 1969. For USA delivered cars, I recall having read that Mercedes Benz arbitrarily fixed the date of change of the model year each year with their dealers.
The details of the car were not related to these arbitrary model years. If a dealer had, for example, four cars in stock with manufacturing dates spread over several months, the ones sold one day prior to this arbitrary date would have a model year one year earlier than those sold a day after the model year change over date. With this system one of the cars with a later VIN could easily be registered as a year earlier model than the others if sold before the magic change over date.
If you want to be absolutely sure you are restoring to the original, use the VIN number as your reference. You will see that changes in details listed in Pagoda Notes as mentioned by BobH above always refer to the VIN.
If you have received the photocopy of your data card from the Classic Center it would be helpful if you could post an image here which could be referred to by all in answering your specific questions. If you do post an image, please blank out the key details in case these might still be valid.
Again, welcome to the group.