I've had a giant 27" Lime Green Schwinn Varsity from a police auction a few years ago. Don't worry. I'm 6'8" and this bike was made for me! I'm finally working on it, converting it to a SS (does that bring down condemnation and contempt from the Classic & Vintage crowd? I'm new here...). And I realize I don't know the bike's vintage.

Where should I look—and how should I interpret what I see—to figure out when this lovely piece of Chicago steel was forged?

Thanks for any help you can offer.