There is likely a reason the carbon was painted over.....
I wouldn't waist the time personally but if you choose to, get your hands on some gun wash from an autobody store, paint thinner and such won't do shit to a paint with a catalyst, you'll be there for days. Gun wash will not wreck the carbon, I typically use it to wipe down sanded carbon to clean it before applying clear coat.
Keep in mind if you go down this path you will have to sand all the carbon (don't worry about burning through, use 500-600 grit paper) and re-clear it.
Like I mentioned, a lot of work for something that may be damaged underneath.