I’d throw Dent in there as well. He has managed to run well in a district that’s fairly typical of PA as a whole (maybe a little more conservative than most, but not by a lot).
Of Barletta, Gerlach, and Dent, I’d say Barletta is the most conservative.
I don’t think Dent would be a good GOP Senate candidate, given that he’s pro-abortion. Bob Casey, Jr. would kill him in the Western PA and the T.