as a new BB i used a standard 40mm thing that needs to be hammered in... (dounno the english name for it).. works perfekt.
using a standard 170mm crankset will give you only a little ground-clearance. It's tight but it works (if you do not intend to turn it into a fixed gear ride). If you can find a shorter crankset, prefer it to a standard one.
changing the fork: I took a long 20" fork and cut a very long spacer out of an old aluminum-frame. that steep standard-stem I got from ebay for 2€ but it will work with any other.