Micdundee , You should go by a pro-shop and shoot your arrows through a chronograph ( to establish arrow speed) and have them weigh your arrows to see how many grains they weigh. Then take the information and figure your KE :

arrow weight(grains) x arrow speed x arrow speed = KE
450,240

There are some programs that can help if you don' t have access to a chrono, but your going to have to know A LOT about your set up ! :

I' d go by a shop ! And if your bow is well tuned and your shooting under 270 fps ......I' d go with fixed blades !