Some work has been done on future Donohue MLW S2 switcher locomotive. Already equipped by Atlas with a factory Loksound decoder, this kitbash it relatively straightforward.
The cab roof was modified in the same fashion Merrillees of Toronto did before selling this ex-CP unit to Donohue in the 80s.
The big issues are the truck sideframes and pilots. Donohue locomotive rides on AAR types. Unfortunately, the older Atlas sideframes aren't incompatible with their new tooling. I the past, I always had bad experience trying to fit sideframes on other locomotives. I'd be curious to know how people install them on trucks in a sturdy fashion.
The other problem is the pilot. Footbars were removed and new steel sheets were fitted on each side of the steps. The locomotive frame is cast metal, making it hard to rework without making a big mess and I'm not very fond of the idea to extend the pilot with styrene bits glued on metal. Not very reliable in the long term if you ask me. But I have plenty of time to figure these issues and decide how to handle them.