Much as me preference is for a J36, I can see a lot of sense in making it the 812, like the J36 is was a loco that had a long life spanning pre-grouping, grouping and BR eras, being buitt from 1899 and the last being scrapped in 1963, it has a pretty preserved livery, but also it could be released as a railroad version in the Thomas range as Dougal or Donald, which were 812s
Jim