Looks like a standard 45/45 to me so it should fit
Edit: the full curve builds use these: http://www.bonzbikes.com/index.php?option=com_content&view=article&id=30&Itemid=4&lang=en
Looks like you need a semi intergrated
Edit 2 : http://www.tartybikes.co.uk/internal_headsets/basic_internal_headset/c88p10869.html tarty says these fit...
there are some good ideas in this thread. and there are some plainly stupid ideas in this thread, 20" to 19" brake adaptors is one of them. 19" wheels is industry standard, get over it.