Pizza in Naples

You can definitely go see the Archeological museum that goes along with the Pompeii artifacts as your day! Sorry, no help on the pizza....

Trianon or Da Michele are both pretty classic places near the train. I prefer Da Michele but both have long established reputations.

I would consider at a minimum visiting the archeological museum and doing a walking loop from the train (Which could take a couple hours minimum).

Though I don't often follow RS suggestions for eating, one of my favorite places in Italy is his suggested Salumeria Pasquale Carrino. Truly a fun, fun guy and a great sandwich. (A couple minutes at most from the museum)

From his Naples in the extreme article:

While trying to find cheap eats near major sights for my guidebook users, I wandered behind the Archaeological Museum and met exuberant Pasquale — owner of the tiny Salumeria Pasquale Carrino (Via Salvator Rosa 10). Rather than ask the cheapskate “how much” question, I just let fun-loving and flamboyant Pasquale build me his best sandwich. I watched enthralled, as he turned sandwich-making into a show. After demonstrating the freshness of his rolls as if squeezing the Charmin, he assembled the components, laying on a careful pavement of salami, bringing over a fluffy mozzarella ball as if performing a kidney transplant, slicing a tomato with rapid-fire machine precision, and lovingly pitting the olives by hand before ornamenting his masterpiece with them. He then finished it all off with a celebratory drizzle of the best oil. Six euros and a smile later, I was on the street in search of a suitable bench upon which to enjoy my affordable and memorable Neapolitan lunch.

Make the Archeological museum a priority, to see all the art that came out of Pompeii. You will of course have time for a pizza, too.

We had good pizza in 2013 at Pizzeria da Gaetano a Porta Capuana. It's less than a kilometer from Napoli Centrale. Plenty of reviews on TripAdvisor.

In 2009 we ate at Pizzeria Trianon (Da Michele was closed). Best pizza I have ever eaten. Simple and delicious.

http://www.ilmattino.it/mangiaebevi/lenews/le_classifiche_del_mattino_le_20_migliori_pizzerie_di_napoli/notizie/318749.shtml

Sorbillo's on via dei Tribunali was terrific as well.