True; you want to document it with photos and be thoughtful, not just blast away with degreaser & steam-cleaning. If resale is the goal, maybe leave it as is. For the cars I've kept around to enjoy, I've never understood leaving leaks and worn-out parts, but other things like wear on paint & such free me from worrying about perfection. I've always had a thing about cleanliness on my stuff, but as the saying goes, they're only original once.
Photos would help - and they're always interesting - and should illustrate the level of survivorship and any attention the car might/might not benefit from. At this point, there's not enough info.