Essentially no. I have been asked before, but the only chassis close to small enough is the Tu-Koppel chassis, which is a little too long in the wheelbase, too small in the wheels and runs somewhat over enthusiastically by all reports. But mainly the motor in it would stick up through the top of the firebox and be very visible in the open cab. Also the model would have to be entirely redrawn as the parts are just about on the line for printability in 7mm scale so it wouldn't be possible in 4mm. Scaling successful cad up to larger scales is easier (though pricier - double the size=8 times the volume of material).
Sorry but I don't think I could produce a version of the model I was happy with using the existing print processes in 4mm/ft.
You could of course always come on up to 7mm scale, eyesight tends to force people up the scales in time anyway!