Pirate Cycles should still have the Manic Mechanic hub adapter that you can use on the Schwinn Stingray OCC Chopper rear hub and the sprockets also can be sourced from Pirate Cycles! I'm pretty sure azBill has a lead / source for rear drive sprockets. Have you seen the sprocket on AZBill's stretch Cruiser. Hope this helps with your search.
Try to look on your local craigslist, you might just find a Schwinn Stingray OCC Chopper for a really good price. Also try the nationwide craigslist post, if your interested in finding a chopper on the cheap!