It takes a stout heart to weather an expensive brass locomotive but I think weathering a locomotive transforms it from a “product” to a “model”. I’ve deliberatley been heavy handed because I’ve never seen a 44 in any other condition than filthy.
Dirty 44
Morpeth In O-Scale 
Looks Great Trevor.
I like you have a 44 class memory that goes back to the days of the North Coast Motorrail service double 44’s thundering through the level crossing at Woy Woy when I was young, some thing that has stuck with me and is possibly the thing that kept me in the hobby from a very young age with out ever moving away to other pursuits like so may do. One thing I remember was the greasy buffing plates a little dry brushing could simulate this nicely to further enhance what is a great finish you have archived.
Happy Modelling
Chris