Thanks for the comments, rockers!
Bill: the tuner/VU graphics were all made up in Publisher, just like all the button function labels.
I do believe I'm settling on a medium gray for the button functions, basically the gray tone from the rock finish. I was leaning towards black for the text, as Scotty suggested too, but that won't work around some of the functions that have a black background below the tuner. Gray should tie it together nicely!
I just need to re-jig some of the function text templates for optimum fit and then send them off to get printed.
But I will reprint the tuner/vu graphics and replace them with a colour much closer to the right green.
Rock On.