I have an older layout that was made with a lot of O-27 track with some modified Lionel and Marx O-27 switches that have epoxied O-45 and O-60 curved track to open up the curves for certain situations but the engines listed here also run quite well thru the old O-27 curved track with no problems and if someone criticizes your overhang of the boiler, just ignore them. It's your layout not theirs. All engines below are listed as O gauge in the catalogs and believe me they do run quite well on O-27 curves and switches
Looking at the picture you can see there the curved section of track was cut off this old Marx switch and a straight section was epoxied in place on . You can use any curve you want also to make it fit your particular situation.
Engines listed are: K-Line GP-38 2301 diesel,
Lionel 1201 Pere Marquette 2-8-4,
Lionel 8977, 0-6-0 B6 switcher.
