Welcome to the forum and to the EMGS
There is a manual sheet on the EMGS site,. If you look under Members Area>Manual Sheets. You will find in section 3 a sheet for the Hornby Bulleild pacific. it contains notes on both thee original and rebuilt versions.
There are plenty of conversion sheets for many other locomotives. Have a browse
You will also find a lot of advice on specifics on the forum as well