I don't believe it is a Schwinn. Three reasons: The chainring is not pattern normally used. The seatstay-seattube junction does not look like a Schwinn (they tended to use rounded and not squished ends). And the brace bar between the two down tubes is not a feature I've noticed on Schwinns. Of course I could be wrong about all of this.

BTW, very nice pictures. Thanks for sharing.