From the research I have done I am questioning that this car could have sat for a couple weeks waiting for parts?
Does the car have some unusual option like JL8? I ask, because my car's # is way before this one and it made it off the line on time. But, even if there was a hold up, they would not wait till it was built to assign a VIN #. There is definitely something not right about this car. Just looking at that small area revealed in the picture, I do not see anything that looks right regarding everything seen around the tag and the color of the firewall itself. The tag, IMO, is real. I suspect trim tag is not for that car or body is re-VIN'd.
If having a BB car is important to you and you want to insure that for investment purposes, I would look at something less modified that has some evidence it is what is on the TT and paper work (real) is always the Holy Grail in owning a pedigreed, documented, Muscle Beast. In lieu of paperwork, if you can find an old codger who has had their car for eons, like me, I think that carries some weight as to documenting by having old pictures of car BITD.
Is the poll for the tag or the car?
You state, "The car seems to be a big block". What do you see on this car that can substantiate your opinion?