What would the PA-3 have been?

Never mind the nomenclature. Alco didn't (it seems) care very much abut model names, and different Alco documents apparently disagree. The original "Diesel Spotter's Guide" used PA-3 for the last 2250 hp PA built (the ones without the drip strip" and porthole on the sides, and with certain engine upgrades), more recent rain literature uses PA-1 for all 2000 hp and PA-2 for the 2250 hp series, and (I have read that) at least one Alco document uses PA-1 for all the 2000 and 2250 hp units built, reserving PA-2 for the proposed 2400 hp version.
What I'm interested in is the unbuilt 2400 hp PA. Alco apparently drew up specifications for such a unit, but no railroad ordered any. But what would it have been?
I have just come across an article (in a railfan magazine from the 1990s) confidently asserting that Alco offered a 2400 hp PA powered by a 16-251 engine. (Subsidiary question: the 251 is slightly longer than the 244: would this have necessitated major car-body redesign?). But they could also have offered a unit with the final 244 variant (244H?), actually used to power the 2400 hp Dl-600A. Does anybody know what Alco offered to the railroad market?

Hummm....
Look at the dates. The last PA (Dl-304D for the cabs, Dl-305D for the PB units) were built in 1953. The first 2400 hp Alcos, the (16-244 powered) Dl-600A, weren't built until October 1955.
The Alco volume (volume 2) of Kirkland's "The Diesel Builders" cites two Alco documents, from 1952 and 1953, both assigning the model name PA-1 to both 2000 hp and 2250 hp units, and suggesting PA-2 for an improved, future, unit: specification 304E/305E is mentioned. But the 304E/305E was to be a 2250 hp type!
I'm sure that if a major railroad had come around, check book in hand, asking for a reasonable number of 2400 hp PA-somethings in, say 1956, they would have built them. But as it is, I don't see serious evidence of anything beyond the Dl-304E/Dl-305E.
So my guess is that Alco never put serious effort into designing or marketing a 2400 hp PA.
(Though, given the similarity of the 2250 hp Dl-600 and the 2400 hp Dl-600A -- note that these models used the same GT-586 generators as the last PA built -- it would surely have been technically feasible for them to have designed a 2400 hp "Dl-304F". I just doubt that they ever tried.)