Longer seatpost?
 

I absolutely love my old Schwinn World Sport but I know it's a bit small for me. I need a couple of more inches in height. Is getting a longer seatpost an option? Mine is right at the safety line right now. LBS has aluminum ones for $19. Along with a used saddle for $15, I may be all set. Thanks!

You can always go for an ATB seatpost to get the extra height. But remember, it you are increasing the height differential to the handlebars causing you to bend over too much for your comfort. Also, the top tube may be a bit short, causing you ro feel cramped. In order to get a comfortable fit, you may also need a new stem with a longer quill and/or extension.