Hi Chris,
I highly recommend Carl’s book as well.
Before you cut into that bamboo, though, you should try to make some PVC shakuhachi, because you WILL make mistakes, and it’s better to make them on cheap plastic than expensive bamboo.
This link has some simple instructions :
http://www.fides.dti.ne.jp/~sogawa/englishpagepvc.html
You can find all the materials at the hardware store. One tube of grey ABS electrical conduit (I think they come in about 12-foot lengths) and a package of joints will probably cost less than ten bucks, and you can make several shakuhachi with it. The PVC shakuhachi sound surprisingly good, can take a beating, and are waterproof (so don’t crack like bamboo), but more importantly, you can apply what you learn making these to making the bamboo shakuhachi. Making a bamboo shakuhachi that plays in tune is really difficult, because unlike the PVC tube, the bore is not perfect.
Here are a few links that will really help you out. The first is an archive of a site that is no longer active, but is a fantastic resource:
http://shakuhachiforum.com/viewforum.php?id=10
The second is still active, so you can ask questions here, and maybe get answers from other members of the forum.
http://www.shakuhachiforum.eu/f11-The-Workshop.htm