'Original look' is at least debatable, if not a myth. If you're serious about history, then preserve the scratches as well. Clean them, and, if needed, add some conservation wax or alike. Nothing that can't be removed later on again. For storage/use in a controlled environment like home / office / museum without intense stress there is no need to be protected against more than necessary.
Your question touches a rather sensitive area: How to handle heritage. And as with any emotional topic, there are various viewpoints and answers.
Actual museum strategies are geared toward preserving the history, not just some fictitious perfect state. Every prop has a history. No matter whether they are funny stickers on a screen, holes for a reset button, or faded key caps for the most used keys. These markings carry at least as much history as a certain special edition paint job, if not more.
Especially when considering that our computers are usually a mass produced wares. Maybe compare it with a book. Lets say an ordinary 1890s physics school book. Nice find. Now take the same book with markings of a school boy. Less interesting? Shouldn't they be removed? To make a perfect book again, maybe. But what if the kid was named Albert and later became somewhat famous? Is a flower on page 32 now more important? Well, I'd say it doesn't matter, as it tells something about the user and how bored he was during that lesson. No matter if he later became famous as a scientist or lived an ordinary life as butcher.
If we want to preserve our heritage, we need to think about history, not shiny things.
Of course, being the techno-nerd I am, I will always prioritize functional restoration above everything else. But as soon as that is given, history gets priority.
P.S.: Feuer frei :))