Will the Lionel 2344 (2354) run fine on O27 gauge?

Lionel's F3s will run on 027 track and smoothly as long as there are no switches.  Bottom line,  beware of 027 switches, especially the 1122s-not sure about the 1122Es.  Many years ago I ran F3s on a 027 4x8 platform without switches and personally I thought they looked pretty good running on it.

Thanks for the insight.  I have four 1122 E switches so I imagine I will run into problems with the NYC locos.

you will only run into problems on the 1122's on the diverging track. As long as they go straight through you will be fine.

The cover for the pw 1122 can have the offending corner trimmed away and refilled to clear tanks and "rocker panels" (I don't know the RR term).  I did it to one for an E-33's tanks before giving it a designated line all it's own.

Cut off a triangle shape of corner with one slice, and fit back a piece of plastic, etc. at a 45° the two walls. You're rounding the corner slightly.  Some paint, maybe sanding, and after a bit you'll hardly ever notice or think about it. I think Lionel points this out at some time or another too.

It doesn't take much trim on the switch covers.  I ran my F3s on 027 track for many years.  If the trim spot bothers you, hide it with a piece of tape.

I was under the impression that the 1122 E model was redesigned to allow the larger diesels like the 2344  to pass without striking it and all of my switches are 1122 E's.  They seem to have smooth corners by design, unlike the original 1122's.

Not sure about the 1122s.  I can confirm that their brown MPC-era derivative the 5122 will clear an F-3 fuel tank.

Lionel's F3s will run on 027 track and smoothly even with 1122(E) switches.  Bottom line,  I've been doing this on our O-27 layout since about 1971, they even squeak through the few 1122(non "E") switches.

How about a pair of O27 Alco's from K-Line?  They come up for auction from time to time and have the lightning stripe look of the F3s but are smaller.

That's what I already have, A and B 2023's but I wanted the NYC locomotive which would be much more commonly found where I live than "Union Pacific" engines.  I can't imagine UP would have been anywhere near NY state but I'm not a rail road historian so I can't speak to that question