I went to take a look--it's an odd decal set that has seen some age but doesn't seem right. sport-touring frameset with a 26.8mm seatpost. I have no reason to doubt it's a Schwinn, and based on the paint, dropouts, & seatpost cluster, it looks to be an '86 Prelude. The current owner says that the person he got it from raced--maybe this was a winter trainer.

SN begins B7, but I can't make out what's after that.

Here are a couple more pics: