1970 Dodge Superbee Inheritance?

Hi, I inherited my dad's car. I learned from him and his friends that it is a very rare model that they only made 20 of. I would like to put a little money into it and have it restored if I know I will get a lot of money out of it. How do I get documented proof that this is a rare car? Also, how do I know what its original paint color is? Any further info and advice (especially from you mopar-fanatics like my dad was) is greatly appreciated!