Originally Posted by
Bad Lag
Measuring externally, the top stack height measures 1.117" and the bottom is 0.549" for a total of 1.666".
So that's
42mm in a size that makes more sense for comparing headset sizes. 
That gives you quite a bit of stack to work with. In your case you could even look at roller bearing headsets like the classic Stronglight A9 or the more modern
IRD (single) roller drive headset (roller bearings in the bottom and ball bearings up top) or even the
IRD double roller drive headset.
I have the latter on my own very tall bike and so far I really like them.
EDIT: Seems like I was too late in answering. Lots of good tips up here.