Reboring German 30.5 cm guns offers little strategic gain

Could Germany have rebored retained 30.5 cm guns to 320 mm for a quick and inexpensive battleship armament?

The proposed conversion offers too little improvement to make an attractive battleship weapon; its engineering cost and feasibility remain unexamined.

The proposal starts with retained German 30.5 cm/50 guns, understood here as weapons from the First World War period. Reboring them to 320 mm would still produce a battleship gun, but the modest calibre increase would not create a particularly capable new weapon. The objection is that the improvement would cross no useful performance threshold. That makes it a poor compromise between speed, cost, and quality; the engineering feasibility of the conversion remains unexamined.