Look up the Giordano70 kit. All the 70 series ovens use that core, they simply have different enclosures.
A proper Neapolitan vent will not retain more heat, it will actually lead to less heat retention due to a largely uninsulated portion of the oven, especially on an oven that small. Trust me, I have built and owned ovens with and without them. That said I highly doubt fornobravo has used an actual neapolitan vent and instead I am sure they have simply routed stainless pipe back over the oven and to the center with a couple elbows to give the LOOK of a neapolitan vent but not the function of one. Few people in this world even understand how they function.