That frame was hand brazed in Schwinn's Koster Ave Paramount shop. It's geometery was copied on Surly's Long Hual Trucker almost exactly. Weighs an extra couple of pounds over a modern welded frame, much cooler. If you're going to actually ride it, I'd ditch the original wheels and upgrade to a set of 700C rims with a cassette freehub. The stock center pulls should handle the 4mm drop needed, otherwise I'd file a little bit.

Here's mine, all I had was the frame so I had a free hand, modded the rear stays a bit so I could fit 35mm tires: