Thanks guys.
Crooketarrow there are a number of 68" long eastern bows in the Alleley and Hamm Encyclopedia of Native American Bows, Arrows, Quivers. Certainly seems to be the upper range of what is presented in that book, but 68" is not too long to be representative of these bows.
Beartail, you nailed it. They are smooth shooters, and yes a good hunting arrow weight is what these bows like. I never shot anything lighter than a 600 grn out of it, so didnt think to mention it.