I bought a 79 and rode it to Sturgis two years ago, this year I did the same with a beautiful blue 78. It was practically gifted to me. X2 on the timing belts, I bought gates belts from Rock Auto, I hear Napa is very reasonable also. If you can tune a cb750 you can tune a gl. My pegs have never dragged but then I'm chicken. I do ride mine everyday and around town, it feels nimble riding it and stops well. I seem to spend about a thousand for new Michelins, battery, water pump, seals, timing belts, and a tune up / carb clean.
I have to remember to ride my cb750's to keep the carbs fresh. L0L!. There are a couple GL threads in other bikes also.