Why could an A Body not have been an F series prototype?
Numerous examples of N41 and N42 exist. Coding depends on year and applications.
M is a legitimate 70 VON letter and A bodies with an M VON code exist.
Numerous models came with Chome tips standard such as Super Bees and Coronet R/Ts
I've stayed out of this thread for a while but was was intriguing about the first post is the information supposedly on the tag. There is nothing that was posted that makes the tag info suspect or indicates by the data posted the car is not legitimate. The one thing that is interesting is it is supposedly a 383-4speed A/C car.
IF a car like this WAS built, all of the codes listed by the OP are codes you would expect or could find on the car described.