the Hornby model used the same chassis design for all of its Bullied pacifics. The chassis having a clever little plate that gets reversed depending on which wheelbase is required.
The manual sheet 3.2.3(4) is the sheet that you want. After Douglas wrote it, I was the second guinea pig to try out the conversion following the instructions. My only failure was in the quartering of the wheels. But the possession of a GW wheel press fixes that problem.
The only other thing to note is that the special crank pins are no longer available from the society stores. But this can be overcome by fitting the Gibson crankpin nut upside down and recessing it into the coupling rod.
The manual sheet is in 2 parts as Douglas found on his second conversion that the chassis had been “improved” with the rear pony cast in.
I have recently acquired a model of United States Line for conversion. This seems to have chassis that is between the two versions.