Please Help!

The car i have is pretty complete, A 1970 dodge challenger minus paint and the most important a vin and fender tag. It basically has no numbers to link it, the car has had i believe 4 owners and i am the 5th. The vin got lost somewhere between earlier owners and the fender tag as well. I got the car because it was a rag top, an original 4 speed and as far as i know a big block. This is where i ask the true mopar heads what to do. I know there are cowell numbers and numbers somewhere else, what do i do to get closer to understanding/getting the vin for my car please help!