There's no need to paint it if you don't want to. It's your car and it can be anything you want it to be.
However, if you're going for a factory correct look, there's a lot that can be done to help your car look more original. Since you're wanting to continue to make your car look "original" here's a few things that are much easier to fix.... (PLEASE DO NOT TAKE THIS THE WRONG WAY, your car is VERY nice, but here's a few things I noticed).....
Put the correct wrinkle finish on the dual snorkel
Paint the cowl area the correct black out (the front rad support blacked out too)
Get a correct voltage regulator
I think the correct carb spring for a 383 is green?
Black out the wheel wheels with correct black sound deadener (if you haven't already.
The mark on the front valve cover should be a 3 digit number (engine code on the buildsheet)
Heat shield should be black.
Transmission mount should be yellow.
leaf springs should have a colored paint dab, not an X.
and I think the foot panel should be the same color as the door panel.
I really like your car so please don't take my comments the wrong way. Just trying help as you seem to want to have your car looking stock and original. I would double check anything I suggest as I might be wrong. Also, I think you got a great deal!
As for the White Challenger, I do think it's worth at least 50K and maybe even over 60K to the right person. It's a VERY clean and nicely done car. Don't see many of them THAT nice.
Thanks Cody!! , I will have to have it painted...if its not right it's not in my collection....I keep learning......