I am currently doing a frame off on my 67 and the color I want to paint it is Royal Plum which was the original color. The only problem I seem to have is locating the paint, I had apint mixed up at a paint store by my house (Chicago) but it really seems like a maroon instead of the factory color, which by the way I only have a factory 67 swatch of. Does anyone know what paint company would have the accurate color so I don't regret it in the future. Thanks.

Are there any examples (cars) of Royal Plum in your area? If so call around to the body shops and find out which paint distributer (PPG, Du Pont, etc.) has the "gun" (paint camera) that will scan/take a pic of your example. From the scan they can create the paint recipe. I suppose you could do it with the paint swatch you have, but a car would be better
See my royal plum car in my sig.

The main paint manufacturers(ppg,dupont,etc) will be able to mix the original code for you.But it is very hard to get an exact match,the metallics used years ago are not the same as today.The color camera(spectrometer)just pulls a formula out of its library that is close.After dicking around for a year trying to get mulsanne blue for my chevelle,I settled on a late 90's corvette color.You can get something close to the original color but it might not be exact.

They tried scanning the the swatch but said it was too small to read. Dale your color looks to be the same as I have on a sample, so maybe they did mix it correctly. And no I have not seen any cars in my area that are Royal Plum. Thanks for the pic.

What is the source for your swatch? If it is a GM dealer swatch it is close as printers ink can get it, which is still closer that a photo, digital or traditional or something off the internet. Royal Plum is a dark color so you example may be right.
Check to see if you have any of the original paint hiding under a decal or sticker (trunk lid? door jams?)
Dale