That looks great! I have the same amp, I am planning on doing up a switch in a 125B with a second jack and third switch to control the reverb too. The only different thing I was considering doing was replacing the red channel LED with a red/green dual LED. So that on the clean channel the switch LED would match the amp panel LED. I'm not sure if current flows down that line to light the LED in that state of switching, so I guess I will just have to do some good old trial and error.