Here is a picture of a 90K mile one owner unrestored fastback from the recent show in Springfield. 7F02C2009xx. Can't read the text because it is off.
The one in my garage that I checked has, unfortunately, a melted lense.
Most of the 67's convenience control package lights I've owned and seen, are all dark (can't read the text) when the light is off. When the light is on, the text can be read and is in color (red or blue). The remainder of the lens is very dark - black if you will. There was a recent attempt to determine when the design transitioned to white text on a colored background - 68MY or earlier - but not much activity on that.
I think it is safe to say that there was no white text on any "early" 67MY cars.