integrated headset: visual alignment frame-fork

Hello,

I have a frame and the outer diameter of the headtube is 45mm, and
headset is CaneCreek compatible (IS-2).

What should be the diameter of the fork shoulder (some call it crown)
for proper headset mounting and proper optical alignment of fork and
headtube?

thanks,
geos

ps. I've found only one fork which has explicitly stated this dimension
on its package (example http://tinyurl.com/aq3t9). I have the feeling
that this diameter is published very rarely. Instead I can see "for
integrated headsets" information, and, at least for me, it's not obvious
for which one, because they differ in size. Do you have the similar
feeling, that it's not easy to choose the right fork for integrated headset?