Don't try to date it using that online tool where you type in your number. Go to the Schwiin forum and look in the pinned threads for Schwinn serial number reference. No need to take it anywhere, just measure the head tube as @49autocycledeluxe described. It's really hard to find a bike shop that is into older vintage stuff. They're outfitting Lance Lycra for his next assault on the Tour de France. What's the distance between the mounting holes for the chainguard?
It's settled, it's post war, forward facing dropouts & built in kickstand and looks 26, I don't think Schwinn made a postwar 24 in. straight bar?, just put a 26 in. rim & tire in there, wouldn't fit on a 24!