Having built a 5" Stanier 2-6-4, I started by enlarging the "Jubilee" drawings (from ME), but after acquiring a dimensioned GA (published in Railway Modeller, I think), I realised that Martin Evans had made everything very over scale.
Send me a PM, and I can send you a PDF of the GA, as well as a JPG of a side-on photo of a full size one, just out of the shops. (The same picture that was published in ME).
Steve