I'm warming up to basic PPCs. I really am. Problem is; the Orion is not a sniper, with it's low arms and ample torso pod space. I mean, it can work, but it's not ideal. Even one ERPPC runs too hot for my tastes, and does not do enough damage alone. Maybe coupled with a Gauss, but then your firing solutions are completely different. So, that's out. I just avoid ER PPCs altogether.
You want to go with a pair of reg. Large lasers, or ER Large. These are very versatile weapons that will do well on your multi-fighter Protector.
If you're absolutely stuck on sniping. you could configure the right side of the mech for sniping. Go with one basic PPC in the right arm. And my "ghetto Gauss" solution in the right torso-- AC10 + AC5 (group fire). This way you can stand behind cover and snipe with a smaller portion of your chassis being exposed. Slap a pair of meds in your left arm and left torso for close work. Maybe even an SRM if you have the room.