One low-risk way to see how the paint will look and go is to find a relative or friend (usually retired) with an airbrush setup, like the kind of guy who builds model airplanes and/or deals with model locomotives. Have him paint the removed bottom plate with lacquer, you may call it nitrocellulose over there.. It's low risk, because unlike enamel, lacquer can forever be removed with little effort by just soaking the plate in lacquer thinner, even many years after it's been dry.
Lacquer is harder than enamel too. Plus most any modeler will have ample black lacquer on hand, the airbrush will do a great job as well.
The proper way is to reverse-plate the brass to get the chrome plating off, as paint is said to adhere to brass better, but for fun with reversability, may as well just clean the chrome and paint it to see what happens.
The engravings are filled with a crayon like product called lacquer pencils, sold at micro-tools.
ANother cool thing about lacquer is that touch-ups are easier than they are with enamel, because the solvent in the new lacquer applied over the old coat re-dissolves the old coat so the old and the new flow together nicely.
If you like how the bottom plate wears and looks, then get the top removed and do it too.. but getting the top off requires special nerves and tools, not something that can be done with pliers and a hammer.
Just a thought.