Welcome and thanks for the photo. With the flat top Bings and what appears to be an ATE brake caliper, I'd say it's a 1979 or '80 model. Looks unmolested, too.
Being in Sandy Eggo, you're near forum member Mike Valenti who owns a magnificent restored R65. He checks in on occasion or you could PM him through this forum and intro yourself. He really knows his Airhead stuff.
When posting tech questions, please do include the model year of your bike. There are a few subtle differences they may effect your answers.