Welcome to the Skylines and SAU! Keep in mind you have a Series 1 so various series 2 bits won't fit unless you change other things, for example, Bonnet, Headlights, front bumper bar etc... Taillights are interchangeable and I personally prefer the series 2s.
Engine wise, Coil Packs and Airflow meter for example, will not swap between series' either. But ALL this info will reveal itself to you if you spend way too much time reading through SAU as it has all been covered many times over.
Sorry to hear about how you came about owning the car and good on you for wanting to complete your mates project.
Read up and learn about it, figure out what you want from it and do it right.
oh and the more doors the betterer.