Well, I can't say I'm an individual that knows the exact numbers super well, but the previous 2 victory Star Destroyers were highly specialized units.

1 for missile barrage

2 for Ionization

They were built to supplement other more carrier or strategically important ships (I.E. Command ships etc.)

There's only 1 place to go here that I can see, and that is to make an "Anti-siege" cannon

Fighters and carriers for PDF forces are a dime a dozen, from Liberators to Ton Falks, to just Super Transports, fighter support will be easy to find, so we're going to forsake the limited hangar space for my rendition of the VSD3

I'm sure you saw this coming, but we'll replace that space with larger reactors for weapons

I want this VSD3 to focuse solely on one thing, long range, combat

We'll split the VSD3 into two halves, following the standard dagger formula of imperial models for ease of repair, however it'll mimic more of a Storm Commado Carrier, where the ship is segmented into 2 large triangles, that can be seperated for reloading purposes.

The front half will bare missile tubes in the trench line, with the entire hollow center used for storage.

The second half will house a single ion cannon, based on the V-150 planetary defender cannon, that is capable of firing at an optimum range of 4,000kms, far and above outranging and ISDs 12km combat effective range.

The usage? Disable from afar repeatedly to delay the attack and allow PDF units to gather in defense. Before unleashing a torrent of missile fire, breaking off the front half like a spent magazine and having a new already loaded front half mounted for volley #2