Here is my 1972 Genuine Mexican Super Bee.

Si seƱor lol. Ok it's neither a Dodge or Plymouth branded car in Mexico. Technically it's a Valiant Super Bee by Chrysler. After 1970, there were no Plymouth branded cars sold in Mexico. Valiant was a brand unto itself in the Chrysler of Mexico portfolio. So there was Chrysler, Dodge, Valiant and Dodge Trucks sold in Mexico.

To get it registered in the US, you need to have it legally imported by a Customs Broker who will draw the paperwork. Once you have the paperwork, then you take it to US Customs where they verify that the paperwork is correct and will conduct a physical inspection of the car. Finally you pay the applicable duties if merited then you get the paperwork (from US Customs) indicating that the vehicle was legally imported into the United States. If the car is 25 years or older they are exempt from EPA emissions.

Once you have the importation paperwork, go to your state's DMV and follow their guidelines to register the car.
I can't imagine it would be much different from importing my Monaco from Canada. It took longer to get someone to tell me the paperwork required, than it did bringing it across. Canada customs people I spoke with were not helpful at all. The broker I found was heaven sent.