I always brine pork loin or chops. I use 1/2 cup Morton Kosher salt, 1/2 cup brown or turbinado sugar, a couple of tablespoons of soy sauce and a couple of tablespoons of whatever rub I put on the outside.
As far as rub, I use a variety of popular BBQ rubs. My favorite is Plowboys BBQ Yardbird with Simply Marvelous Cherry or Apple a close second. A simple rub of salt, pepper, garlic and poultry seasoning is good, too.
I usually cook pork loin at 325 or so until it is 135 internal then let it rest before slicing. It will be 140 - 145 internal after resting.
But, it you want to cook at a lower temp I would do as Bludawg suggested.
Another option would be to cook it at 225 - 250 until it is 130 internal and then sear on all sides over a hot grill until it is 140 internal, then rest and slice.