I picked up a 1998 MIM Nashville Deluxe that the frets need polished on. I’ve never done it but I have some lapping film I use for sharpening straight razors in 12,9,6,3,1, and 0.3 micron. 12 micron is roughly 1200-1400 “grit” and 3 is 8000. I figured it would work well as it’s very flexible and won’t leave a mess. Get some of the fingerboard guards and go for it.