If the VIN plate is on the bike, you can find the year from that. If the VIN plate is not on the bike, the VIN should be stamped in the left side of the steering stem and should also be on the horizontal cross member that connects the left & right sides under the seat.
The engine will also have a serial # stamped on it and don't worry that the 2 #'s aren't the same; they never are on these bikes because the frames and the engines were made at different factories and married together later.
Find the engine & frame serial #'s and post them on here and everyone will tell you what year your bike was made. (You can actually find it out yourself on this site if you want to do so).
Regardless, welcome to the forum and good luck with the build. Download the service manuals and parts lists for your bike from this site, print them out and use those as the starting point. Take lots of photos, keep the build thread updated and post questions when you have them (note I didn't say if...you WILL have lots of questions). But the good news is that there are guys on these forums who have done complete restorations several times and I can guarantee you that any question you have will be answered. Good luck. Look forward to following this one.
OH...and one more thing. Take the time at night to find some complete restoration threads and read through those. You'll be amazed at how much you will learn from reading through the threads of other builds. A lot of the posters here will put their build threads in their signatures at the bottom of their posts, so just click on the links.