Considering there are pictures documenting the process, I would say its pretty firm. Smith had specific procedures to follow.
This is just my opinion, dont take it personally...everytime there is a discussion of 1969s, there seems to be one car that is an exception, that would make me wonder....
Wasnt your car sent overseas and modified ?
It may not be a good example to use as a model. Knowing Mr Speegle and others who have documented these items, they tend to take years to come to their conclusions, constantly tweaking their conclusions, looking at many cars and concentrating on cars that are known not to have been modified.