Putting famous British Shunters into this game is pretty pointless: They did exactly what they were intended to do: shunt rolling stock around at individual stations or marshalling yards, and were never built for public service or speed, just traction and pulling power, the class 08 probably being the best example: high traction and very small for her output.
I’d like to see the Castle (4073 class) and Deltic classes in the game! Seeing the then beasts of the railways: Classes 37, 52 and 55 would be good. The Deltic had two engines and her pulling power was such that it meant that no more than one engine was ever switched on, if a breakdown occurred (very rarely) the crew simply put the other engine on.