OK, so what you appear to have is a 1973 body with a radiator support that has been replaced. No big deal there, it happens.
But as far as the dash VIN goes, it came from another car and swapping one VIN number from one car to another is a federal crime.
You should try and get your money back if possible.
You should also contact your local law enforcement agency, tell them what is up. Their involvement will help insure that you get your money back from the seller. They can also check to see if the 1973 body was stolen. If the seller is the one that swapped the 1970 VIN onto the car the police will deffinately want to talk to him.
Please keep us posted as the events develop.
Barry