Does anyone have any data that gives optimal intensity level for peening 15-5 PH steel? Specifically I want to peen using steel shot a rotor to increase fatigue strength and surface compressive stesses.

only for reference:
aircraft structure,15-5PH,40~43HRC,intensity 0.012"~0.017"A, coverage 2.0

I think thats far too high.

8-12A , 230-330 shot, full coverage.
Shot size can be changed based on part geometry if you have tight fillets or small holes that need to be lance peened, but I think thats a good place to start with the given intensity values.

Your question however requests data, which I do not have, only experience.