I have a 68 Nova with 4 doors. It has rust but not much. I was wondering if it was worth restoring or not?

If by "worth restoring" you mean financially, probably not. Unless it is real nice (needs little work) the cost to restore a car can easily exceed its' value. This is especially true for a 4 door because it has a much lower market value than a 2 door. But if you like the car and plan to keep it don't let that stop you. Of course any work you can do yourself will be a big savings.