[924CarreraGTP]

The tank can be drained by simply pulling the fuel line off of the under side of the tank at the rear. The fuel pump will probably have to be replaced. Some people soak them in cleaners and get them to work. Once you get the tank flushed, fresh fuel, new fuel pump in, and battery, locate and open up the fuel line in the engine bay and put it down in a plastic container. You need fresh fuel in the tank with a 1/4 bottle mix of Berryman's B12 Chemtool. Disconnect the coil from the distributor for safety, and then bump the starter to engage the fuel pump. This will clear the old varnish out of the fuel lines, and fuel filter from back to front. Do it until you get clean fuel in the container. Rather than dismantling the whole fuel system, you could plug the fuel line back in and see if the car comes to life. Plug the coil back in of course. The B12 will clean the fuel system even after the car is running. It will eat paint off of your car body too. So be careful with it. Seafoam is too weak. Use Berryman's. I've seen it dissolve rust... That's the quickest way, but have a fire extinguisher handy when working on fuel systems, and do not smoke. Don't spill fuel on shop lights, etc, or kaboom and emergency room... Worry about making the car run first. Once you get it running then you can start changing the oil, antifreeze, and transaxle fluid. If your fuel pumps or electronics won't work check relays and fuses before wiring. Porsches have fuses and relays for every system. They are simple if you know what to check.
I've gotten cars like this running in a matter of minutes this way.