Lexington hulls and the value of an extra 1910 slipway

What would the major naval powers do if each received a Lexington-class hull and a connected slipway in 1910?

They would probably complete the hull as a battlecruiser, but powers with the strongest supporting industry would gain most from the extra slipway.

Each major naval power would probably complete the hull as a battlecruiser because a fast capital ship was immediately useful. One extra ship per power would not radically change the balance by itself. The more important gift is the connected slipway, especially for Britain and the United States, which had the industrial system to keep it productive. A yard still needs steel, machinery, labour, and suppliers, so physical building space alone does not create sustained naval capacity.