Not trying to influence your decision, but I happen to ride with a couple of tall guys who have gone the custom route. One went Ti and while he is quite happy with his Guru, even he would agree that it is not nearly as stiff or light as the other guys Parlee. The fact that Parlee make so many bikes for really tall people suggests you might be able to get a test ride on a very similar bike to what you might eventually order.

Their size chart makes me think that you might even be able to go stock. Although if you are set on Ti, this option is probably not for you.