Need a starting point for an S scale 4-4-0 or 4-6-0

[TinGoat]

Suffice it to say that it falls somewhere between S and O scale. It is larger than S Scale but smaller than 0 Scale and there is a lot of back and forth on whether it should be defined as 1/50th or 1/56th.

Well, if you are looking for information that fits model railroading at ~1:56 you'd do well to take a look at 55n3.

It has a lot of information on blending S and O scale for 5.5 mm scale.

O gauge at 32mm would work out to broad 6-foot gauge which was common in the late 1800's before most railways converted to standard gauge.

But for standard gauge you would have to custom make your track and rolling stock at ~25.5mm which is a little broader than S-gauge ~22.5mm.

S-gauge is close enough if you're not a stickler....