I used to shoot Easton 800 spine arrows when my draw weight was between 20-30#. With my Altus, my local archery shop recommended a 600 spine for my 43# bow. Currently using Easton Venture arrows. My archery friends have arrows which range from 400-320 spines with 45-55# bows.
I’m not sure how much the length matters beyond comfort/weight shedding since less arrow means lighter arrow. My shop cuts them to an appropriate length that works for me, so if your length works, the important part really is the strength of the spine and giving your old arrows a good flex to check em and make sure there aren’t any cracks. Don’t want anything exploding!
If you do have a nice, local shop, I highly recommend stopping by to ask for suggestions or getting your arrows cut down if needed!
Edit: Also, if it helps, I have a pretty short draw length too. I think it’s between 27”-28”. If you check out “arrow spine chart” from different manufacturers, they also have spine recommendations depending on arrow length.
Oh dude! It’s a game changer! I used to squint and hope that somewhere “between line three and four” was 45 yards. Single pin really makes shots so much more consistent once you’re calibrated.