Although none of the kits are perfect, and one promised kit has never been released (Dragon - USS Pennsylvania 1944), the last few years have seen a huge increase in the classes of battleship available in plastic in 1/350 scale. What I can't find is anything about a New Mexico class battleship.

I wonder if a Pennsylvania/Arizona class kit could be used as a start. Although the superstructure is completely different, the clipper bow was apparently the major change in the hull

Anyone tried building one of this class in the post 1941 fit.

USS New Mexico and the Pennsylvania/Arizona are two different class of ships

The change from the Pennsylvania class hull to the New Mexico class is almost certainly too much of a stretch. If you wanted to start from an existing hull, a better start would be a Tennessee class hull which is the same hull with the clipper bow. The major difference between those two hulls would be the underwater hull protection which may not be a factor in a conversion. Of course, only resin kits exist of Tennessee, so that may be a non-starter as well, though at least there is a kit unlike the NM. Also, you would have to start with an unrebuilt version as the rebuilt Tennessee had additional bulges with a 17' broader beam.

A thought might be to make a mold of a TN bow, cast a replacement then attach it to PA hull to make a mostly plastic NM hull. Then you can start the extension conversion to the rest!!

That was my thought
A quick look at the deck plans of the USS Pennsylvania and the USS New Mexico seem to be almost the same from the first casement gun position to the stern - not perfect, but very close.
Only the clipper bow would be a major scratch job. Much of the base superstructure was similar.
With all of the work needed to create a late war Pennsylvania, it doesn't look like that much more is needed for a New Mexico class which doesn't appear to be modeled in any post 1941 configuration either in resin or plastic.
I need to lay the deck plans over one another to see how much change is needed.

To the best of my knowledge the only US non fast battleship kit in 350 is the Arizona in plastic. A lot of modification indeed... the Az was 16 feet shorter besides lacking clipper bow.

Iron shipwrights did a 350 resin kit of the NM. There is one on ebay for $325 plus 21 shipping. No plastic of her in any scale I can find ( 1250 metal one)

My recommendation is to bug trumpeter into making a cage mast ( CA MD WVa or TN). Then you have something much closer. LOL I been begging for years. Would love to see a NM class as well...but they they only promised us a Rodney/Nelson would be out 2 years ago,and it still ain't here. Also waiting for a Baltimore/Pittsburgh