Check the old posts for MG Magic and call them about manuals etc. They carry a lot of parts such as wiring harness. Maybe somebody else has their number handy and will post it for the 100th time.
Your first order of business is to find a VW only parts supplier and mechanic (often the same place). You will find that VW’s are their own special little niche in the old car world. As far as the year of the motor, can be determinede by the serial# which is located on the case right below the carburater. Two things to remember: the year of the engine may not be the same as the chasis, and the engine may have been modified which might be an issue with smog depending on where you live. Chasis serial number is located on the “yoke” of the pan, center of the “tunnel” which runs between the seats and right behind them. Generally covered by carpet on these kits. There’s an access cover right behind where the number is stamped. DMV will probably want to see that. If you get chummy with your VW guy, he can show you the artful ways in which those numbers can be changed if necessary…”for informational purposes only” as they say on those websites devoted to manufacturing drugs, bombs etc,
I hope you enjoy your car. If you enjoy mechanical things, VW’s are a lot of fun. Because of the dune buggy and custom market you can get just about any part you can imagine. Don’t “re-invent the wheel” before you check out what’s available “off the shelf.” Just about any problem you have has been had by a million guys ahead of you and already solved. VW Beetles changed little over their long life, hence the ecconomics of the after market are a little different than for other old cars with a smaller customer base. It’s all still available and generally for very little money.