Here is a video I did in the past of one of my Silver Fox A Classes running on a Railroad Deltic chassis. I have no problems with slow running or pulling power.
If you look at Broithe's picture behind the cab you will see what looks like a large black box with a radiator and exhaust that is part of the torque converter the trucks fuel tanks are also up there as well behind the cab.
I assumed when you said 5 bogies you were talking about wagons. Didn't realise you pulled the bogies of your wagons and just coupled them on their own behind your 071.