True, the cylinders are wrong, but those are easy enough to change.
I think MDC slide-valve cylinders would fit in with a little fitting. The
Arbour and Rivarossi engines are neat little units, but I'd rather not use
them. The only Arbour engine I had, their SC 4-6-0, never turned a wheel.
The driver axles were too big to fit the slots, and the tender-mounted
motor was designed to drive the engine via a 1" long piece of tubing that
also served as drawbar! It did not work. Maybe the A3 is better.
The Rivarossi engine is actually capable of running, and pretty well,
but I would rather start with an old-style kit engine for a kitbash because
they are sturdier.