That is a beautiful 914. Before you embarked on any projects I would get it to a shop that knows these cars well and go over it front to rear looking for any issues that might not be apparent. Even on cars as nice as yours there might be something that was missed by a previous owner.
I would then focus on the fuel system to make sure it is up to date and 100% reliable. Stainless steel fuel lines in the tunnel and new rubber anywhere else with new clamps and filters. That includes taking a look into the fuel tank to see if it looks clean or not. Don't forget the fuel tank sock filter.
After that for me it would be electrical. I would look for anything not original. I am not a radio or alarm guy so for me if it did not come factory, it would be removed. I would want to make sure the factory harness and fuse block were all up to snuff and the correct fuses were installed. It is not unheard of for people to swap in higher rated fuses when they start blowing a particular fuse. I would clean all of the ground connections and tighten them. Check to make sure every single item on your car is fully functional. Once you are sure all the wiring is 100% good, then I would add whatever you desired so you know it is added correctly - stereo, etc.
Of course brakes are a big deal on our cars. At the minimum, unless the seller had just done it, I would flush the entire system and check all the rotors and pads. Make sure the emergency/parking brake is correctly adjusted and functional. Eric Shea at PMB performance in Utah
http://www.pmbperformance.com/catalog.html is the go-to guy for all things brakes.
Actually, Eric is now doing complete restorations so he is a valuable source for anything on these cars. We are blessed to have many people here who are dedicated to maintaining and restoring our cars. Chris at Tangerine Racing who sells the SS fuel lines
http://www.tangerineracing.com/about_us.htm is a terrific guy too. So many experts supporting our community and they are all available to you.
Mechanical issues are next. Make sure the suspension, engine and transaxle are in good repair. Oil leaks? I personally can't tolerate them. I realize on an older Porsche that is more of a challenge than say newer Porsche cars, but it is possible to have a 914 that does not leak. Do a leak down and compression test to make sure the motor is healthy. If the numbers are good, unless it had recently been done, I would do a valve adjustment and complete tune-up to set a base line for driving.
Lastly, comes all the cosmetics. That is more involved too. Weather seals (Mikey914 at 914rubber.com
http://914rubber.com has almost anything you need in this department), any visible body rust, bumpers that are not aligned correctly, exhaust systems that are rusty, have holes in them or are leaking.
OK, I have kind of rambled on here as I have my first cup of coffee.... Sorry and best wishes on your beautiful car.