[Phlogiston]

They actually turn dull over time as the lacquer cracks and yellows (lacquer can "yellow" to white or even black depending on conditions). If old lacquer is still intact it can be re-polished to a high gloss.

It is probably not a good idea to try to recreate an aged finish. Just ask yourself how that finish is going to look after a few years of ageing - too dull and too yellow.

If you have to refinish aim at factory-correct and then let time take its course.

As I mentioned before, scratches, water stains, loose veneer and other defects will be most visible in a gloss finish. So if a cabinet is in less than perfect condition and a person can not perform repairs, a less-than-gloss finish (while not original) might suit the novice radio restorer. Just look at it as practice for the rare, glossy radio you will find some day.