The spine of the arrow is determined, in part, by the length of the arrow. The longer the length, the weaker the spine. A convenient length of arrow for your 25.5" draw length would be 27", which would give you a half inch more than you might actually need if your draw length increases with experience, a not uncommon occurrence. So your arrow would be a little stiffer than normal, because of the short length. For that reason, I would suggest a 500 spine arrow, like the Gold Tip 3555 or equivalent. You could start with a 150 grain tip, and if the arrow is too stiff, you could try a heavier tip or add supplemental weight behind the insert, which GT is designed to do. If the arrow is too weak, you could cut a half inch off the front, which will stiffen the arrow. Lighter than 150 grain broadheads are available, but are not optimal for hunting, in my opinion.
Clearly, it would be best to do this experimenting on just a shaft or two until you figure out what you want.