I live in NJ near 78 on the border of PA. I've taken the route you've proposed many times, both from New York border through to 81 in PA. I've not been on 81 north of 78 in PA, so I can't speak to that, but what I can say is what you propose is a decent route. There is no major construction on any of these roads, except for 287 near Parsippany, but that is north bound. There is one major hill on 78 near mile 11called Jugtown mountain. Trucks get down to about 35 mph sometimes, but beyond that it is an easy trek, and you should have no problems.