My impression is that once you have consolidated your execution, and exhausted the easy initial progress, you PS will go up with your squat. I would say that for every 10# you add to your squat, something between 3 and 5 will end up in your PS.
At some point, your limiting factor might be your ability to actually lock the bar solidly overhead; in that case, some OHS might be helpful, if you have the time and want to limit the number of failed reps.
Not very helpful, I know.
IPB