I'm sure I'm not entering the spirit of this topic -and there is much to admire in the skills, tenacity and hard graft involved here - in saying this is a bit of 'If I wanted to go to Limerick, I wouldn't start here'.
Why not save a lot of time and effort in developing new Colletts from the new Hornby models? Some of them may just need sides being overlaid: the roof, ends, underframe, bogies, general profile and measurements are so much better than the Railroad versions. Should I get my coat now, or just admit to being a heathen?