Wow, the exact bike I had for my 15th Birthday (second hand in 1979). Mom and Dad really pushed the boat out to get me that one, especially as Dad had been made redundant earlier that year. It wasnt that old, but had endured a hard life and needed a complete overhaul, which is why they could afford it, plus it was one of my dad's friends so he did us a favour on the price.
I resprayed in a similar, but nicer metallic turquoise, but kept the stripes. Claude Butler sent me a set of transfers, after some interrogation to prove it was a genuine CB, frame number and also details about the running gear. The Reynolds 531 transfers were like gold dust in 1979!
My rebuild upgraded the brakes to an ultra 7 cassette with, if I remember correctly, an SR Silstar double crankset, with Shimano front and rear derailleurs (no indexing back then). I kept the standard steel wheels as I could fix a puncture in mere minutes, and where I rode (everywhere) I needed something with some strength.
It rode like a charm, and I used it for school for 3 years in all weather. I must have done thousands of miles on that thing, and only stopped when I got my second motorcycle, at which point we had to part ways as I needed the money for insurance and better riding gear. I did always regret selling it, but have recently got a slightly more recent Dalesman, which fits the bill nicely.