"Vintage" bikes

[OakLeaf]

You'll do better with a steel frame. Spreading the dropouts will let you put on a modern (10 or 11-speed hub) rear wheel. If you don't convert to at least a 9 or 10-speed cassette hub, you may have a hard time finding NOS freewheels when the one on the bike wears out (if it isn't already).

Besides the frame not being cracked, make sure it has no rust. As far as frame alignment (whether or not it's bent), it may be hard to tell from a visual inspection, although some defects in the paint can alert you to a bent frame. Again, steel can be cold-set into good alignment by a framebuilder, and some LBS's may have a jig and the skills to do so as well. But if you don't plan to race it, if it shifts okay, stays in the gear you put it in, and doesn't wobble on high-speed descents or turns, then the alignment is probably close enough.