Assuming you mean the 0-4-0 steam loco and not the diesel you would be more than ok. The Porter 0-4-0 is typical of small industrial type locos that were built around the turn of the century thru the 20's. This would be very typical motive power for a narrow gauge industrial/logging /mining operation. The Bachman engine looks pretty close to as built, so it fits your time period and maybe calls for a little modernization. By 1942, generally these locos had been thru several owners and seen a lot of repair and rebuilding. If that's your thing, you could add an updated headlight, and perhaps a new cab (the old wood cabs often burned, rotted, or became otherwise unusable, and were often replaced with metal home built jobs). I can't see from the pictures I have if the engine has an air pump, but if not, it would be appropriate to add one, although some quarry and logging outfits never did use airbrakes.
Additionaly, these engines were rebuilt with what was on hand, dependent on the budget and skill of the outfit's mechanic. By the end of their service, the were highly individualized. You're modeling a period that was proceded by the revenue short 30's and subject to wartime 24 hour traffic demands and restrictions on repair material. If you favor the highly weathered look, it fits here.
One more thing I might mention here is that narrow gauge outfits were big on used equipment. During the thirties when many narrow gauge roads went bust or reduced operations, surplus equipment was sold off at bargin prices. Thus you have an excuse to run just about anything that your line's management thought they had a use for and could pick up cheap.
Sounds like a neat project, hope this helps.
JBB
should have made myself clearer and say i meant the gas mechanical 0-4-0 ...
thanks for the good info though jbb, i will certainly keep that in mind. I dont wanna go malcolm furlow on the weathering but i want to have a 50/50 mix of second hand stuff and "home built" rolling stock.