Well someone will be along who eats and breathes arrows, but for my opinion, you could look at any number of arrow dealers (I like Surewoods douglas firs myself) and give them a call with your set up and they could probably tell you better than most what would work. Test kits are one route, but I'm too cheap and impatient for them, even though I usually regret not getting them. I like the douglas firs because they're strong, stay straight well, and take a beating. Good luck and welcome! I do know longbows tend to favor weaker spine but don't know much about your bow. For a good starting part you can either use the 3rivers archery spine calculator (always been good to me) or include more info on your set up for those not familiar with your bow. Such as shelf depth, string material, desired tip weight choice, etc. however all anyone can give you is a best-guess scenario since each set up can be unique due to form and such.