You may want to ask this question in the C&V forum.
Your bike may not be ideal, mostly in being designed to handle racks; however, the tire situation is not one I would worry about. It should handle a 1 1/4" tire alright (32mm) which is doable on most non-paved roads (no personal experience with the Alcan)
The 5 speed can be made to work, so it isn't absolutely necessary to 'upgrade'
You can have a successful trip with this bike, including fenders, racks or higher speed drive trains (130mm spacing) without any real trouble. Since the frame (not the vintage) wasn't designed for loaded touring there will need to be some compromises; however, it is doable.
Similar vintage Fuji 27" wheel frame with 700cx32mm tires, 8 speed drivetrain, and enough luggage capacity for short credit card tours. More capacity could be added with p-clips (or similar tech) and a rear rack.
