It will be interstate highways virtually all the way unless you want to explore. That means divided two lane highways. Some of them will have a posted limit of 70 or 75 but almost everyone will be going 80 and it is easy to find a lonely area to do a test run up to triple digits to make sure the carbon is blown out of the engine.
Once you get back closer to Yankee land the speeds will drop but the first day will be some wide open country. There are gas stations for stopping all along the way.