Thanks so much for the compliments guys!
Wolf Watcher, I'm honored that you think I can answer that very difficult question! I'll give it a try.
The long arrows you speak of are probably "composite" arrows with a long foreshaft and a stone point. This style was used everywhere west of the Mississippi before European contact. In many ways, they resembled the earlier atlatl dart. East of the Mississippi, arrows tended to be made in one piece, also quite long.
After iron trade points became available, the foreshaft and stone point combination was discarded and the trade point was attached in its place. The draw lengths remained the same.
There is a lot of debate about how the buffalo was hunted. Personally, I think the majority were killed after being disabled, tired, or in a confused state. The technique of riding along side a buffalo and shooting it from horseback was probably reserved for the most skilled warriors/hunters who didn't care abut the risk of death (very few).
Anyway, if you want to make a plains quiver, decide if you want to make "pre-contact" arrows (with foreshafts and stone points) or arrows with trade points. Then make your quiver long enough to hold the arrows with maybe a half inch of the arrow sticking out the top.
When you see a short arrow with a stone point, I believe you are looking at a "tourist" arrow. It's just my opinion, but I think a foreshaft was used on the vast majority of hunting/war arrows that had stone points, especially if the arrowhead did not have a stem.
Hope that answers your question.
Oh yeah... yes, I plan on going to the classic.