My maths indicates that you will have just over 200 feet per second of shot speed. That would require S280 to S230 using Jack's chart. That is much larger than CCW14. My conclusion is that you would not be able to achieve the required intensity. Do you agree?
Even if you could achieve the desired intensity, I would advise you don’t do it. Peening at that high of velocity is not peening its blasting. You will be abusing the surface of the part in my opinion.