There are a few buying FAQs out there, but look at the hell hole (I'm assuming you know where it is), the rear trunk under the tail lights, behind the seats (floor pans and longitudinals), and bubbling in the door handle/sail panel area. You need to pick which is most important to you: driving a 914 or building/working on/fixing a 914. If it's driving, then you need to save pennies and buy a good car. 914 restoration can easily overwhelm people who are expecting a quick project.
But be patient and the perfect car will come along.