How about this method.
I NEED a GRCW 119 Cross Country DMU
Worsley Works sides and ends
Modded Lima underframes (cheap off Ebay, centre car chassis off a donor conversion)
Triang Mk1 roofs
MJT vents
Lima Gangways
Plastic card to profile ends
Scratch insides
Will be running on a kit power bogie when purchased with simple brass bogie frames for the other 5.
Resin casting for bogie frames (using modded Lima frame beefed up).
Resin casting for roof dome with Derby style destination blind copied from a Lima DMU converted to 116
So using Scratch aid, RTR, kit, home small batch produced, and a small amount of scratch.
Do I care what it is?
No.