When shooting roundball you better keep the powder charges low, around 50-60 grains. As for the conicals, I would worry more about accuracy and less about velocity. You put a big conical in the right place and it will get the job done.

I shoot 460 grain No Excuses out of my Black Diamond XR. Another lighter but very accurate load are the 270 grain Buffalo Bullet Ball-et. I shoot them with 80 grainsand they would be an excellent deer load.