Country style ribs-- not ribs at all-- come in a couple varieties. The loin type is recognizable by a pinker, leaner meat, and typically the absence of any bone. The other type, usually just labeled "country style ribs" (no loin), are cut from nearer the shoulder and are deeper red in color, marbled, and often have chunks of blade bone in them. Since what you have is labeled loin, I am assuming you have the former, and those I would treat more like pork loin-- a higher-heat cook. Maybe not as high as 350, though, as carry-over heat might take them past where you want them in terms of doneness. You could foil, or you could brine (probably too late for that now), either with the goal of preventing dryness.