First try autosol solvol, brilliant stuff. If that doesn't work then use superfine wet and dry paper, 2000 grit ideally, used dry not wet, rub over any scratches. 2000 alone can give a mirror finish without polish. Finish off with autosol. Avoid decals though. If the marks are deep then we can buff these out at our workshop.
Please always try this in an out of sight part of the frame first, under the bb etc, to see what results you will acheive