Essel Engineering chassis

Picked up at the 3CAG group show, this is an Essel Engineering Chassis. Ready to run, it's a heafty bit of kit at 700g in weight thanks to all-metal construction. I've wanted to play with one for some time and was just looking out for a suitable project. Then this appeared for just under half price, so we have a solution looking for a problem.

Powered by a 380 sized motor through a gearbox and then onto the axle with beveled gears, the chassis runs smoothly, and not too fast when fed with a 9v PP3 battery. 

My bargain has obviously been fitted to something, judging from the extra brass bracket it's aquired. I had to do a little tweaking with an Allan key too to fix a crank and set the gauge to 45mm. Nothing taxing, but offputting if you've not done this sort of job before. I took a while to work out when the thing kept stalling at one point on the revolution, and I've fettled many a model railway chassis!

So, what to do with it? In the past, plans have involved an IP Engineering "Shelley" - but the one in our collection now has the proper chassis.  

Now, I'm thinking that a powerful battery-powered diesel would be useful. Something along the lines of Roundhouse Engineering's Bulldog would do the job. I'd need to shorten this chassis, and mock a body up in card. Then, some brass sheet for the finished model to produce something as strong as the underpinnings. A design will be required as the wheelbase is 78mm and Bulldog is (I think) shorter then this. I'd like to be vaugely prototypical, so am open to ideas if anyone wants to drop something in the comments.