Actually, that is the original receipt (11/08/79) stuck in the wheel, and the owner's manual in a small portfolio is on the floor. I bought it "in the box" and set it up myself in '79. I put it away in the mid-80's, and it hasn't seen the light of day from then until now. The reflectors are still in their original bag, as are the toe clips, and I have all the original packing material. The Brooks B17 was an upgrade when I bought it. I'm leaving it free of extras, as I did originally, and have a laden down touring bike to complement it. This always worked for me. When I bought the DT, I also had a brand-new Skyway and a brand-new Hill Topper (saw somebody yesterday riding a later model Hill Topper T15--rare). I did quite a bit of riding on the Skyway and Hill Toppers, and sold them in the early '80s. I had kept the DT just for long distance "joy rides". With your SSD, I would just try to keep the components you use consistent with the type of bike it is. Since it is riding season, the best thing to do now is get out riding and enjoy the summer weather.
My other road bike is a "Foodge", and I rode about 50 miles on it yesterday. Since the picture was taken, I've added a Cat's Eye bar-end mounted mirror and a Cat's Eye detachable headlight.