70s era road bikes are plenty sturdy if they were sturdy to begin with. The key thing is maintenance. If not much has been done for it over the years it may need some work. Kraynick's on Penn Ave might be a good place to go with a bike of this vintage for an opinion.
One thing to consider is where you are commuting in Pittsburgh. It can, as you know, be hilly and a newer road bike, or a hybrid or mountain bike, would have more gears.