About 4-6 hours of sanding and polishing by hand - could have ended up with a mirror finish but lost interest, plus I ended up with clear coat over the top so I would have lost the mirror finish anyway.
Steps:
600, 800 and 1200 grit wet and dry sandpaper
Autosol Metal Polish. (tried Brasso and Silvo as well but they were hopeless)
VHT Clear Engine Enamel (took some of the shine off....)
Notes for next time:
Start with a coarser sand paper (maybe 400) and use a sanding block to make sure it's flat. Not the easiest shape to sand though...