#1 wiring, every wire run and connection. First thing where salt water corrosion shows up. And long term problems unless you completely retire the boat. Especially in hidden areas that could not be rinsed or cleaned. Eventually corrosion is going to show up in places that are covered and can't be seen. Nothing on that boat was designed to be used in salt water. Except maybe the motor. Aluminum and wiring does not play well with salt no matter how good you clean and take care of one. You may buy the boat and get years of service out of it, just be aware of the potential problems and expense you could be facing. Also this is just my opinion but that motor is awful heavy for that boat so I would sure check the transom and the transom bracing for cracks or broken welds.