Oh boy, that engine looks stunning! 
I have to confess that I bought the Minicraft kit last February when I saw this thread... the kit is still unbuilt though :/
You wouldn't happen to have any wip pics of the engine build?
Regretfully not, but if you have a look at the red sprue, you´ll notice that the sides of the cab are converted and the front end and walls are about 6mm lower above the water tank. Water tanks length is kept original, but the boiler is cut at about the length of the water tanks. The steps, base plate, bumper plates with bumpers and couplers and frame girders are the only parts from the black sprue that I used. Base plate and girders were cut down in lenght of course too. There is no cab interior apart from the hand brake crank that is moved forward. The base plate is largely cut away and the boiler has less than its upper half to make room for the motor.