I'd try car paint restorer like T-Cut on the stem first. I was amazed what it did on a badly faded fluoro/splatter Eldridge. Not perfect, but way better.
under bowing pressure and seeing it in that picture i tried to t-cut the stem butt to no avail. The bike is going to be resprayed. until then the syncros stem will remain but then back to the marin one!
need a seatpost for it though - if anyone has one!!!!