RE: Why won't this work?

[Susan Parker]

Hi.

Roundhouse in the UK supply parts from their loco range separately to home 
builders, including a simplified Walschaerts type valve-gear. I believe 
they also do a cosmetic extra bits to make it look more interesting, which 
might be able to be made functional.

I am not sure that the dimensions will work for you but this might be an 
alternative way to go?

See: http://roundhouse-eng.com/tech.htm for a picture and diagram.

A set costs UK# 75.

Best wishes,
Susan.