Hello from Windsor, Canada. I have owned 4 240z and know them well. If you have a solid body, little rust especially frame rails, battery tray, etc., you're off to a great start. Unless the engine has been rebuilt, it will need it and that's including the head. Now you can look for deals for a swap, get the head rebuilt, etc., but if you have never worked on a Z , don't do the work yourself. One mistake with cam timing and you'll smack a valve and $$$$$$. For $3000, you can bring your engine to Datsun Spirit and get back a completely rebuilt engine, done right.
In the long run, you're better off.