May I suggest a different approach for the handlebar bag? Consider going with an '80s Cannondale bag. Significantly more "period correct," especially for an '80s Schwinn. They come in all sorts of sizes and colors. A red or black one would look terrific. Possibly even a silver/grey one. Some will encourage you to keep a careful eye on the bars where the mounting bracket rests and watch for wear and possible cracks. I've never seen any.