That all depends on your physique and the kind of shifters you want to run. Bar width depends on shoulder width; if you're a broad shouldered guy, get some wide bars, and if you're skinny, skinny bars The drop is a matter of preference. If you want to get real deep and aero, get deep drops like the Cinelli Criterium bars, but if you like to stay a litte more upright (probably the best for a commuter bike) get some shallower ones like the Cinelli Giro d'Italia. Also, modern integrated braking/shifting levers are better suited to modern compact/ergo bars.

Have fun building that Somec, I'm building one myself now, the one [MENTION=173992]non-fixie[/MENTION] was talking about.