Yes, of the two roads, the 82 is my favourite. However, it can't be denied the 85 is quieter.
Several years ago, I was riding back to Glasgow along it when they were doing extensive work on the bridge a few miles beyond Glencoe. Almost a mile of it was reduced to a single narrow lane, controlled by lights. They were red when I arrived, I waited as the traffic streamed through, then stopped then I moved off as the lighs changed to green. After a while it became apparent that the lights were not timed to take account of a tired hill climber, returning home on a bike heavily laden with kit and camping equipment travelling at quite a bit less than 20 mph. A stream of traffic lead by several large trucks was heading towards me, accelerating rapidly. I had to pull of the road pretty smartly, and perch precariously at the side, till the line passed, then pedal frantically till I reached the other side of the closure. That was fun.
I am guessing, now, such a situation wouldn't arise, as the awareness of cycling has increased. And it is a beautiful road. But the OP did request quiet roads where possible. It's not the quietest.