The Schwinns are good foundations for motorizing. There are many here owned/built by members. As was mentioned the front mount can present some challenges but nothing that can't be overcome with a little ingenuity and imagination.
Spend some reading time here using the Google Custom Search feature and you'll have plenty of good information to start your project.
Have fun, ride safe.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"