How Lexington battlecruisers could favour the Montana class

Would the United States have built the Montana class instead of the Iowa class if the Lexington-class battlecruisers had been completed?

Quite possibly, because the Lexingtons would already provide fast capital ships and reduce the requirement that led toward the Iowas.

The counterfactual changes the composition of the American fast wing before Second World War battleship choices are made. Completing the Lexington-class battlecruisers could reduce the pressure to build another set of fast capital ships. That makes the Montana class more plausible in place of the Iowa class, although the result remains a possibility rather than a certainty. An older surviving class can redirect later procurement by filling one operational requirement in advance.