I shoot a 29 inch GT 3555 (.500 spine) Trad arrow with 200 grains plus std alum insert out of my 50# Montana at my 28 inch draw and it bareshafts perfectly for me. I would think that with your setup, the same arrow cut to 29 inches or shorter would put you about where you want, but you'll need to bareshaft tune to know for sure. I believe a CE Heritage 150 (.487 spine) would be another good arrow to try with your setup. Just don't cut them too short at first when you start tuning.