Thank you, Rick for your inputs about USS Cowell and USS Johnston. The kit I have got is a SSModel 1/700 3D printed kit. It is more detailed than Trumpeter's USS Sullivans.
I don't post as much these days because of repetitive questions. And access to the ship modeling websites due to the websites not updating security settings that my iMac doesn't like. Many questions that SHOULD be answered from multiple sources are not even researched. I suggest individuals look for and buy the two FLETCHER class pictorial books I wrote for Classic Warships. I strived to answer these configuration questions and provide images.
As for "can" a USS COWELL kit be made into a USS JOHNSTON model. Not having the USS COWELL kit to look at and experience with trumpeter screwing things up on their kits, I can't verify what changes would be needed. I don't know anything about this 1/700 scale 3-D printed USS COWELL (based on what info or copied kit??). One thing I can state is that USS COWELL was built by Bethlehem SB-San Pedro (commissioned 23 August 1943) and USS JOHNSTON was built by Seattle-Tacoma SB Seattle (commissioned 27 October 1943). The "basic" configurations look the same, but there are detail differences.
However, again, who knows what Trumpeter decided to replicate in their kits for the 1/200 scale FLETCHER's. If Trumpeter decided to "upscale" their previous USS THE SULLIVANS 1/350 kit for the USS COWELL, there would be multiple differences. Primarily the bulwarks for the 40-mm and 20-mm guns.

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I just received 3D printed 1/700 full hull USS Cowell and Nueve de Julio. Is it possible to build as USS Johnston and USS Boise (adding catapult, crane and admirals/whaleboat)? Any more modification needed? I appreciate your insights/inputs to help me complete these projects.