There was an article in an early Model Railway Journal about converting Ratio 4 wheelers into 6 wheelers, if I remember correctly. MRJ is renowned for being a little behind the times, so you may have to learn Latin or Aramaic to read it though
Model anything that doesn't fit the Great Western fraternity's view of their favourite railway.
I once witnessed a layout operator being threatened for "daring" to paint a GW loco in BR black livery.