If the paint looks perfect with no flaws in any of the seams it is not original. I saw one original paint duster with a hair in the paint (on driver fender) and seen many original paint cars where it looks like they only used a grinder on the lead roof/quarter panel seams. The lower rocker seams are also finished terribly.

Chrysler paint had a good bit of lead in it so I doubt you can buy the exact paint mix today due to the EPA.

Of all the car companies I dont think any had more durable paint than Chrysler. (I believe GM use laquer in the muscle car years and did not hold up well over time)