Assuming this isn't a troll, you might want to hang out a little on the C& V forum
Classic & Vintage - Bike Forums

If the 19" frame fits you, you can probably do anything you want with it. That's a quality frame if it fits you.
Here's what my buddy did with a Schwinn of comparable age to yours - he had a wheelset built with a SRAM 2-speed auto hub and a front dyno (700c, of course) and this bike is really fast on 28mm tires.



This is my '77 Raleigh rebuilt 3 times since '78 - this rebuild was around a wheel swap from 27" to 700c - you can change the nature of any bike by improving the wheels/tires.
This is my utility bike - it's also very fast and has gears to go anywhere with any load. I rode this with my friends who were training to climb Donner Pass - were climbing 2800' and I rode this bike because it can climb the 18% grade at the top.


If the frame is too small for you, find a local organization that rebuilds bikes for inner city kids - sounds like a great candidate for a 5'4" teenager.