Forgot to add, your arrow choice seems fine other than I'm not familiar with that spine. It may be too stiff OR your up front weight/lgnth may correct . Come up with another set up and build both. Then test both and pick the best one. One of my test arrows will have 2 degree offset vanes, the other will have 3 degree helical. Curious to see if the helical fly my thunderheads any different.