Welcome back to the road! The Fuji Sagre was a fine bike, so I don't think you need to worry about making it better. However, if it has truly been sitting there for twenty years you might think about giving it a proper tune up (changing cable, repacking the BB, hubs, headset etc) and possibly changing the tires. Also you never know, maybe after you put 1000 miles into your Fuji you'll discover you don't want a new bike.