I did my mast a while ago - it's on page 23 of this thread (and here:
http://www.adventuresinbob.com/the-big-re-rig-part-2/) . I just wonder if you should be removing the winches and fittings, Lazz? If there's corrosion under those you might be better off getting all that gone while you've got the mast down.
HG, I used a belt sander mostly and an angle grinder with a blue paint remover disc on it for any thicker stuff (eg. the 2-pac I painted on my boom before I decided not to paint the mast

). Best results were doing long, even strokes along the line of the mast. Can't recall the paper grade.