DO NOT buy a bike unless you know it will fit you. The only way to know that is to either be fit to the bike in person, or to know enough about bike fitting and geometry to be able to translate your personal measurements to the measurements of the frame. The main cause of people giving up cycling is that it's painful and uncomfortable; the main cause of pain and discomfort is riding a bike that doesn't fit properly. Much like shoes.
Older bikes like this certainly can be a good buy, as long as you recognize that upgrades to modern parts may be difficult, and replacement parts may sometimes be difficult to come by. But bike shops will charge just as much for a given repair as they would for a newer bike. So if you're not willing to pay $75, say, for a repair on a bike you only paid $75 for in the first place, then you should assess your own skills and/or local resources (friends or local co-ops/clubs, access to specialized tools, etc.). The benefit of buying a new bike from a local bike shop is that there's a warranty and service policy.
So if you know little about vintage bikes, see if there's anyone you can find who can help you evaluate the candidates. And unless your SURE about what you're buying, it would be much better to stay local and look for used bikes you can actually inspect and test-ride.