Building a (accurate) Montana is not as simple as splicing two Iowa hulls together for length and reworking the superstructure. They were actually wider than the Iowas and had a different hull form.
I will leave it to you to define accuracy to your own personal level. The image below is from the USNHC collection and shows one of several design studies for the Montana.
http://www.history.navy.mil/photos/usnshtp/bb/bb67.htm
Should you choose, you could splice some Iowas together and call it close enough.
Mike Bartel of Imperial Hobby Productions has made some 1:700 scale Montanas which are more accurate WRT the hull form. They were resin, limited production run, and long out of availability.
But fear not, Mike has posted that he is working on a 1:350 scale Montana which he has said will be sold through Yankee Modelworks. I'm not sure what the status and due date is for the kit