Classic Industries and O'Reilly Auto Parts will have everything you're likely to need. CI has a downloadable PDF catalog specifically for the Chevy II/Nova. I've purchased parts from them for my '67 4 door and am satisfied with them enough to recommend them without reservation.
How long has the car been sitting? I would start my inspection by checking everything rubber on the car. Mine sat for 19 years in a barn before I rescued it.
I had to replace the following to get it running reliably:
Tires
Heater hoses and clamps
Radiator hoses and clamps
Generator belt
Spark Plugs
Spark Plug wires
Battery
Battery cables
Fuel pump diaphragm
Carburetor kit
Wheel cylinders
Vacuum lines
Front brake lines (short rubber section near drum assembly)
Engine oil change
Tranny (Powerglide) fluid change and fresh filter
Air filter element
I also had to pull the ignition switch and get it to a locksmith since I didn't have any keys to the car. For $15 he was able to pick the switch and remove the lock cylinder and make me a key for the ignition, doors, glove box, and trunk.
Right now I am into the car for about $500 worth of parts and consumables to get it in running condition. I'm now spending my time and effort defeating the mud daubers (black wasps) that built their homes in the car for almost 20 years. It's messy, but since it was stored in a barn it is relatively rust free.
I also highly recommend Sea Foam for use in the fuel tank and in the crankcase for the first couple of hundred miles, then a complete oil change.
Good luck, and don't forget to take a few before/after pictures. It will make for an interesting heirloom in your family!