Up until 1966, VWs had a 6 Volt, 180mm Clutch and Flywheel. If your engine has been swapped for a later model engine you may have a 12 Volt, 200mm Clutch and Flywheel.
Keep in mind having a 12 Volt system does not determine that your VW has a 12 Volt Clutch. Changing to a 12 Volt system and keeping the 6 Volt Flywheel, Clutch, and Starter is common practice on earlier engines.
Be certain to measure your Clutch Disc to determine which components are needed!