Probably between 40 and 55 lb spine, depending on the variables. Pretty hard to say for sure. Get a couple around 50-55 lb and start with them full length. Make sure your nocks fit the string well and are mounted true and fletch with short, bright feathers. Shorten them gradually until they shoot great. Start with field points and finish with broadheads. If they end up longer than you like, go down 5 lb in spine for each inch shorter. I'll check my stash and see what I have for shafts.