The St. Paul was a Baltimore-class heavy cruiser. I'm aware of one up-to-date styrene kit that represents that class: the recent 1/700 one from Trumpeter. I have the impression that it's a nice kit - though I gather it represents the ship in her World War II configuration. (I don't know exactly what changes she might have undergone by 1950; I imagine her 20mm guns were removed, along with her aircraft catapults, and her radar sets probably were updated.) Later edit: there are some Korean War-vintage pictures of her at Navsource (www.navsource.org - click on "cruisers," then scroll down to the St. Paul). It looks like her 20mm guns were gone, the 40mm ones had been replaced by 3" ones, and the catapults were removed - though the aircraft handling crane was still there. One shot shows a Dragonfly helicopter landing on the afterdeck.
On the nostalgic front, there was a Baltimore-class cruiser among Revell's very first group of ship models. (According to Dr. Graham's book, Remembering Revell Model Kits, it was initially released in 1954 with the name Los Angeles, and reappeared with the names Helena in 1960 and Pittsburgh in 1967. The scale was about 1/490.) It was a typical product of its time: extremely crude by modern standards. Aurora also did a ship of that class, in 1/600 scale. (Modern modelers have trouble taking Aurora warship kits seriously, but it's worth noting that the company was a pioneer in the concept of issuing kits to a consistent scale.) If memory serves (as it frequently doesn't these days), the Aurora kit did appear at least once with the name St. Paul on it. My recollection is that it was a somewhat more accurate and better detailed kit than the Revell one - but that's not saying much.
Those are the ones I can remember. I imagine there's been at least one resin Baltimore-class kit as well.
If I were contemplating a model of this ship, my first choice would be the new Trumpeter kit. Gold Medal Models makes a nice set of photo-etched detail parts for American cruisers and destroyers on 1/700; I suspect a Trumpeter kit dressed up with those additions would be mighty impressive.
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