Part of the issue with your car is that it was a drag car, a lot of drag cars have no vin numbers as the cars are not registered and they are not run on public roads. Don't look too deep into this, it is not worth it for you. If the hidden vin numbers are no longer there, for whatever reason, and all you have is the vin on the dash, then the car is whatever that dash vin says it is, and don't worry about it. If you have a clean title with that vin number, then you are good to go. Remember that if that car somehow comes up as stolen or a swapped vin car YOU will end up paying the price. They will not charge you with having stolen anything or anything like that, but if it was stolen you will certainly loose the car with no recourse, if you bought it in the last 3-5 years you might be able to go to the previous owner, but they probably bought it like that too, so they have no liability, and after the 3-5 year period in most states you hit the statue of limitations. The only "good" thing that could happen, if the car was not actually stolen, but just had a vin swap is that the state could let you keep the car and issue you a state issued vin, which will kill the value of the car. I know that you are probably just curious about the history of the car, but it is not in your best interests to air it out in a public forum.
There are a million possibilities to how this ended up being, and not all of them involved a stolen Boss. That car may have been parted out for whatever reason and bought as a shell, maybe it was a former stolen car that was stripped and it was bought from a previous owner or an insurance company, and converted to a race car. There probably was no title or dash with the car. After it was used for decades in racing, someone decided to put it back on the street, they had clean title with a dash, and just put it on that car to sell it.
I don't know if you have heard of these cases, but there are cases in which the same car shows up with the same vin in 2 different places. At some point a valuable car is either discarded or sold for parts as it is either too rusty or damaged to be put back on the street, but the owner keeps the dash with vin number and title. The title and vin number are sold and someone uses it to create a clone of the original valuable car. In the meantime the actual body is bought by someone who decides to fix it as they find the hidden vin numbers and decide that it is a valuable car. When the body is all fixed up, they go to the local DMV and have an inspection done on the car, and since the hidden vin are there they are issued a title with the original vin numbers. And now you end up with a mess, as there are 2 cars with the same vin numbers.
