The only tutorials I've read where you'd need to include burning involves denoisers. In this case (if I'm correct) you didn't use any filters, so burning would take too long in my opinion. Burning can sometimes make the lineart look too jagged, and it might not darken all the blacks. The best thing to use for filling blacks is the "Polygonal tool" or the "Pen tool", this helps you make a selection around the area you want filled and it fills it to your liking. Just get used to either tool and you'll be fine for filling.
Next. Did you level before you started cleaning, or did you just start filling blacks? It's only because when I look at Ino in the next panel, I can tell that the original
raw hasn't been properly leveled according to the blacks. It looks like you were able to clean part of the whites on the panel but it doesn't seem like you leveled the blacks. It's always easier to level the blacks and whites, then clean whatever is left over.
All the extra stuff you circled must be darkened as well, you probably could tell what was origianl Line art and what was just some scanning dust, so everything that you know is original must be cleaned, and in that case you have to darken them. And of course this applies to all the background art as well, but usually leveling darkens the blacks and whitens the whites.
And nope, rarely does Naruto ever have any grays, and I don't think you have to deal with tones in Naruto either. Which is why it's one of the more easier series to clean in the Jump Magazine.
Good luck, and if you have anymore questions, please do ask.
