Personally i'd leave it as is "good survivor",
if you start playing with it it will show and you'll end up masking it up and going all the way round just trying to blend it.
I have a 3M polishing kit at work for polishing faded/tarnished plastic headlamp lenses. It does a fantastic job on those but having tried it on seats it's noticeable due to the softness of the plastics (i guess it depends on how fussy you are but if you're considering resto you must be)
sometimes 'back scraping' with a Stanley blade does a half decent job of removing the high spots.
Good luck