Here is the deal... If you follow the Federal laws to the "T", you cannot be convicted for possession of an illegal firearm. Where the issues lie are weather or not you are willing to put up with any kind of harassment and legal fees should a rogue cop decide to give you a hard time.
Perhaps the most important piece of advice I can give is DON"T get pulled over in the first place. And if you do get pulled over, DO NOT offer the information that you are transporting a firearm.
Again, follow the federal law to the "T". Firearm unloaded, cased, in the trunk (if your car has a trunk), separate from ammo. DO NOT stop in either of those states except for fuel or to use a restroom.
In fact, I would suggest to you that you come up I-81 to Scranton PA, and then I-84 all the way to the MassPike. (I'll let you figure out how you wish to get to I-81). This will keep you out of NJ altogether, and it is only 73 miles across NY. So you can gas up, take a leak, and grab a bite to eat in PA, and cross NY without stopping at all. Plus the traffic and scenery are much more pleasant.