In that era, gauges were lit with red "peanut lights" - the little dust pan covers you see at the corners of instruments of that era could actually be twisted off and a bulb replaced in flight - I always had a couple in my flight suit just in case. To the best of my memory, red lighting had no intensity control in planes I am familiar with.
However, planes also had thunderstorm lights, usually a cylinder-type object with a rheostat knob at the back, and located above a side console etc to shine directly on the panel as needed. I often turned mine up just slightly to eliminate shadows etc. The A-4 series had two, one on each side.
We also carried a "gooseneck" 90 deg flashlight with a spring clip on the back. We carried it snapped over the chest strap of our torso harness. The lens cover could quickly be changed from clear to red as desired. More than a few pilots came aboard using the flashlight if they had some lighting problems.