I would go with .280 in 26 inch. The NEF has a short action like my Encore, so the 26" barrel wont be so noticable. You will get higher velocity with it in the lower grain bullets but I dont know about the heavier 175 gr. There will be less recoil also. You could call a technician from one of the major reloading companies and ask them what they think. They do it for a living. I have and they usually will help you.