The Settle to Carlisle line set in the modern day is a mainline with heritage line character, This route would fully utilise the Class 66 from GWE as it hauls heavy fright up the steep gradient known as the long drag plus the challenge of careful break management as the player drives back down the other side, with the class 158 providing the stopping passenger services, but trains from the WSR like the class 31 and class 52, or the class 40 and 45 from the Trans-Pennine would feel right at home here as they perform a daily rail tour to Carlisle and back with the opportunity for the player to get that perfect screenshot of the train going over the Ribble-head viaduct.
I agree with TinTin_57 its a great suggestion. In theory with much of the route being double track and rural. Could we get Hellifield to Carlisle? Or even Skipton (80 miles)?