Hi
One shelter that I know 6'5" people have used (more than once...) is the Tarptent Rainbow.
A bit under 1kg , can take a long and wide mat and still have some space around it.

See this thread for example :
http://www.backpackinglight.com/cgi-bin ... d_id=97558depending on your location and because although you will fit in it but the head is not all that far from the fly laying down (less room for your breath to dissipate) condensation could be a problem. (see Benjamin's comments)
This can be mitigated with our "liner" basically a fabric layer that goes between you and the roof area of the shelter. Add 150g for it.
( I just use a Chux inside single wall tents to deal with condensation)
Or if 1.5kg is not too much, the Double Moment was specifically designed for the tall ones.
Note that the thread above also mentions several other shelters.
This is the Double Moment :

franco@tarptent