Wonderful jobs!
Without going mad, the BCFe 2/4 can fit easily a modified motorized halling motor bogie.
http://digilander.libero.it/Bri866/BA/IM...205_221800.jpg
The basis truck Is the follow one, modified by removing the front load, by tilting the motor of 90° around vertical axle and by building the mobile connection with the rest. All has been done with few pieces of plastic and glue. The distance beetwen axis Is very similar ( 1 mm more or less) respect the correct one. The Only problem is that you have to put a good load over the bogie to compensate the removal of the original load without charging too much the bogie itself. Maybe that this wouldn't be a problem with a plastic model, but instead you will Need to put a spring beetwen the load and the front part of the bogie to have a better weight balance.
https://shop.ferro-train.com/HallingShop...le/ANT-ST10-H0M
Also a chassis of and N scale SD40 can be a good start ING point. I have found the First chassis that i have obtained from a toy sd45 from new ray railroad n line. It worked and fitted well. The real problem was the toy motor (too fast) that could be replaced. Howewer Is a good and cheap starting point.
http://digilander.libero.it/Bri866/BA/IM...0207_130501.jpg
Regards,
Brian