There are a lot of posts on the C&V forum by folks who tour on their old vintage bikes. As long as the frame hasn't rusted or been damaged it should be okay. You don't have to spread the rear to accomadate more speeds. Some modern improvements would be tires and brake pads. If I were younger and wanted to do a self supported camping tour, I'd love to ride on one of the French 650B camping bikes with the additional diagonal tubes.
By the way it would help if you would describe the bike you plan to tour on.