If it were me, I'd go for more silver! That orange just screams for a more old-school look. Seatpost, stem, brake levers, toe clips, etc... Maybe a set of those lovely stitched leather bar wraps from V-O. Brown brake hoods... And if you ever pooch a wheel, get silver rims/hubs.

Those would be my cosmetic recommendations, based purely on my own preferences. YMMV. As for upgrades that actually matter, upgrade those clips and straps if you're running fixed.