Greetings from Italy
My 68 Charger RT is PP1, and was done with Sikkens paint. If you use a PPG paint mixer, you can go by application, selecting year and make and you get correct paint shade. Or you can go to an automotive paint shop that sells Sikkens paint, and with the number you can get the correct PP1 paint. Keep in mind that sometimes it doesnt shop as Dodge but as Chrysler. But codes are different even if names are different.
On the Sikkens paint book, it is listed as CHA 66 Scorch Red 407 H5, used by Chrysler vehicles from 66 to 68. It interchanges with some japanese car..will have to check on the paint can