Suzuki dealer will be able to get parts .
https://www.partspitstop.com/oemparts/l/suz/50d3eb68f8700230d8b4afd3/1980-fa50-parts
I'd see about finding another parts bike that has mostly what you need .
Then make one good out of two . Maybe sell leftovers .
Once put together in stock form you should get many years of dependable service .
Mine is doing just fine after 11 years of use . (edited)