Hey Ralph : I think that the ideal power unit for this loco would be to use the Fosmotors Which you can get from Fosworks at : [email protected]
This little unit has a wheel set geared to a nose supended motor and is self contained, thus very easy to install, depending on the power requirement that you have you could use just a few if what you want is the engine to move by itself, or motorise all axles or a fraction of them depending on your power requirements. I understand that it is a fairly mild power unit but on such an engine you could just multiply as you wish and the installation would be a sinch. I knew about this being member of G1MRA where he advertises since ages. usual disclaimer. This locomotive is a very interesting prototype to model. Another solution would be to try a real gearless drive if you can find suitable motors with less than 40mm length and an axle on both ends. This would be more prototypical but, I fear that the speed at which the motors turn would be to great. On my SNCF 2D2 910O I could not use real Büchli transmition as, for one I wouldn't be good enough of a mechanic to do one, but two, I was afraid that it would be too fragile for the great outdoor. A it turns out it has over 20 years of fairly intense running and is still going strong.
Keep us posted on your progress. cheers, Simon