Nice work on the P class, however, there is already several versions of the P in Trainz in both original Westrail orange and late 90's yellow liveries, and a recent update has given them narrow gauge bogies too:
Orange version by Leon: KUID:30073:1011
Yellow version (reskin) by Colhad: KUID2:50587:1011:1
Orange version (narrow gauge) by Mizzle: KUID:144681:1011
Yellow version (narrow gauge) by Mizzle: KUID:144681:1012
Thats not to dissuade your model though AD60, as the above models are pretty old (1.3/04 era) and are coming up as faulty in CMP, so a new version might be a good thing.
As for the W class, I'm pretty sure that the Hotham Valley Tourist Railway's website has the same W class plans which also appear in
A History of WAGR Steam Locomotives, complete with technical info, so that's a good place to start (and yes, the Silverton version was almost identical, save for the streamlined boiler cowling similar to the WAGR S class, and air brakes rather than vacuum).
(Is amazed at the sudden interest in WAGR/Westrail prototype

).