There is a good article in the March 2017 Muscle Car Review magazine about stock vs restoring when it comes to barn finds...

Tim Wellborn acquired a hemi Lime Light Road Runner, and it was the example used most in the article

He didn't have it washed, just had the mechanicals fixed, so it can be safely driven or displayed.

Well, in the article, some experts like Tim, Roger Gibson, and Frank Badalson, weigh on what original parts you might want to be careful with if you get ahold of a cool old muscle car, and why you might not want to restore those parts, as they are far more valuable in original, or as found, condition.

Take the Mopar rallye rim for example, they were originally black, but painted that silver on the outside only, and overspray might be evident on the backside (inside) or not. Or, there might be red paint that dripped onto the rim from the wet brake drums. Those things are important to not paint over or clean up and destroy, if you want top dollar when selling the car someday.

the NOS parts store at the Wellborn museum. Damn. I wish I had a winning lotto ticket

http://www.hotrod.com/articles/restore-conserve-heres-maintain-survivor-car/