The things that you would need to determine the arrow would be:

1. Draw - If you go with a longbow you could loose up to 2" of draw.

2. Poundage at your draw.

3. FF or Dacron String

4. The bows geometry inluding center cut

5. Release, mechanical/fingers - even different styles you use with fingers could effect the arrow.

6. Shooting off shelf/elevated rest even things such as how the shelf is crowned or the riser rounded will effect the arrow

On the other hand, carbons are suppose to be able to handle a wide spectrum. I have/had some grizzly sticks which are suppose to be able to handle a 50-80 pound traditional range (I didn't like them, but other swear by them).

There are probably some other things I left out. The arrows really have to be matched to the bow, but there are some good starting points. I like the chart at FoxFire to get close.