I would say as long as you don't use a large grit and put a shitload of elbow grease on it, you'll be ok. Stay with the finer grits. 2k, even 3k. Or use a polishing disc. Just be careful of the rpm. All you're trying to do is put a shine on the new stuff so it blends w the old stuff.I'm confused about the word polishing in the context of cf. Everyone says you shouldn't sand cf because it exposes the fibers which you'd like to stay encapsulated in the resin they were made with but isn't polishing really sanding. If not, what's the difference. Is there a way to polish that doesn't expose fibers and potentially make the shaft shed?
Hour should do it. If your arm can hold out that long.