Hunting bears in PA is a ton of fun, welcome and enjoy! Where will you be at in southern PA?
All three calibers are sufficient. As long as you are not walking out there with a .243 - you should be more than good.
Between my family, friends, inlaws, and I we use or have used:
30-06, .308, 30-30, 45-70, .338 win mag, 7mm mag, 7mm-08, and .375 H&H mag.
PA is a great bear state - a very aggressive management plan by the PGC has paid off. You could be running into a 150lb yearling or a 900lb bruiser. At the local check station in central PA that I go to, there are always several 300+lb bears checked in and usually a couple that go north of 500lbs.
Edit to add: Also consider what "type" of gun you will be carrying for the terrain you are covering. If you are going to be going up and down ridges through mountain laurel, picking a smaller lighter gun for all day carry might be something to consider.