I was mostly leaning toward the proplusion system. That could be improved to save money. IOWA and her sisters would have to be almost split in half to do it. That's why I thought it might be better to start with the Montana class.
The reason I said to start with Montana is that USS Montana and USS Kentucky BB-68 were canceled. Kentucky was used for parts for other ships.
In the fifties, the bow on the Wisconsin was damaged when it rammed another ship. The ship-yard cut the bow off of the canceled Kentucky and welded it on to Wisconsin. Years later, the USS Detroit AOE-4 was built with the Kentucky's boilers.