Since this old thread came back up...
If you want to poke jets out in standard Keihin sizes, use metric drills. Keihin jet numbers refer to the orifice diameter in hundredths of a millimeter. For example, a #82 jet has a 0.82mm. Inch drills are close enough for baseball, but if you are buying a set of small drills just for modifying these jets, I would suggest metric.