M. Höhne wrote:

Start with lacquer sticks. They are designed for filling in engraved marks. You may find this is all you need, or it might give you an idea for further searching: https://markal.com/products/lacquer-stik . You probably don't need twelve of 'em, but they have a 'find a seller' button at the top of the page.

 
thanks for the info on those--in this particular case, i'm faced with stripping the color from the whole thing leaving bare metal, then getting back to one color for the scale and another for the engraving (for instance, like the red margin scale on a remington 5 with the fine white engravings for the scale)...   wondering if those lacquer sticks would stick to the un-engraved part...?