I was going to list all scenarios using the WCML Northwest and Scotland and 390 below, however a duplicate reply error puts a stop to that.
A search of Glasgow to Preston brought up at least 11 scenarios using the 390 on the route. However it does depend on which 390 you have. WCML South? Virgin class 390(Discontinued) or the original class 390 (which had GNER and Intercity liveries?
As you may know if your wanting a realistic service you will need other DLCs for them to work. Best to check the requirements on the scenario before downloading.
I hope this helps.