Mike Bartel of International Hobby Products (mostly a model railroad company which dabbles in never-were ships) made a resin Montana in 1:700 scale which he sold under his label (now OOP). Mike made the master for Yankee's 1:350 scale kit. Mike is perhaps the best 'expert' on the abortive Montana class battleship.
(You know what they say about experts -- he's the guy who is 50 miles away from home with a slide show!)
No offense to our hosts here at FSM, but the article in the mag a few years back on making a Montana by stretching a couple of Iowas is wrong. You can't get there without a major rebuild.