Carb cleaner or Brake cleaner works just fine. Then you put any tough paint on it and you are good to go.
I own one of the Marlin 60's with the heavy target barrel and synthetic stock, shoots like a house a-fire! I painted that one just to clean it up. The bull barrel was shiney blue, while the stock and receiver (aluminum) were a flat black. So I cleaned up the barrel with brake cleaner, taped off the front of the receiver and put a patch of tape over the muzzle and sprayed it to match the rest of the gun. Looks much better that way and has held up for over 10 years and many trips to the woods. Go for it. The worst you could do it not like it, then you can remover the paint with carb cleaner. 44 Man