Have you gone through all of these sites?
schwinn serial numbers
C&V sub-forum would have gotten you a lot of vintage folks that know old bikes inside out that may never come to this sub-forum. Or is this not a vintage Schwinn frame? Yeah they'll crucify you if it just the bike shaped object from the company that bought the Schwinn name. So be careful! <grin>
Read this with a grin. Only 1% of this is anything remotely serious.