For the rebuilt what if version, I would really go in favour of more aesthetically pleasing solutions that are in line with the rebuilds, and not anchor so much to what was done to the standards in all aspects.
Hull? Yes, like standards, I like the fattening. Do you want to sheer the bow a bit upward? Why not!
Turrets? Yes we leave them as is sure. Just slap more floats on sides.
5in twins, 5 per side, or even 6 (if thats not an overkill, would be better than 4 per side.
Funnels? Now this is where it gets interesting. I dont love the look of those you have, they are too spaced out. I would move them closer. Think of what was done on Renown - when rebuilt, they really made an already good looking warship into even nicer one. Id really put teh funnels closer together, perhaps even both to the center, like on Renown. You can have boats in between, or platforms.
Superstructure - I dont love the pyramids they seem a little cartoonish. But even more so, I am not a fant of the funnel merge like the Italians had on their cruisers where funnel gets blended in. The funnel spacing you have is also reminding of Italian designs, not sure if its good or bad.

So, I would use the Renown as an inspiration in the way you build Battlecruiser into a modern fit, but adjusted for the solutions that the Americans had available to them. I think Renown had many changes - the big superstrucure, new funnels, suggesting better engines and so on.
Lets build a beautiful warship, USN had those. The Standards were always very stubby and some like that, but Lexington is a long hull, go Iowa on it, make it look nice.