Man we go through this a lot around here.
Each state is different in some way. Most states used the engine number as the VIN through '55. The number on the data plate was the Serial Number. Again, check with your licensing authority to determine what you need to get your title. It's that simple. If they want the engine number you bring them the engine number. If they want the serial number you bring them that. Many will require an "inspection" to verify the number.
