Nothing says it needs to be 60cm. If you make a battleship with 6 60cm lances, you basically have an apoc. Let's make something different. There should still be some ret similarities I think because it is a return hull, that's my point.
Since the fluff for this ship says it's trying to replicate the Apoc not the Ret, lets make something that fits the fluff be that different or similar. The point about hull is a moot one. All IN BB are effectively based on the same hull, it's the innards and weapons that change them.
Victory: 365pts
Battleship:12 Speed:15 Turns:45* Shields:4 Turrets:5 Armor:5+/6+
Armament: Range/Speed Firepower/Strength Arc
Port Lance Battery 60cm 4 Left
Starboard Lance Battery 60cm 4 Right
Port Weapons Battery 60cm 6 Left
Starboard Weapons Battery 60cm 6 Right
Dorsal Weapons Battery 60cm 9 Left/Front/Right
Prow NC
The ship trades 4 lances for 12wb, giving it effectively the same firepower as the apoc without the downsides caused by the full 6x 60cm lance armament. The only problem with this is that it overlaps the vanquisher although less so than giving the victory 45cm arms and trying to make it ret.