My suspension guy has had a chat with the Whiteline tech division (and several other companies) and no one is making this bush and even thinking about making this bush for the 3 here in Aus.
Another option he mentioned for additional caster was to extend/shorten the bracket that attaches that bush/arm to the chassis, moving the position of the bolt hole to gain extra caster.
But he also said that he could make a poly one and/or adapt the Focus poly bush relatively easy within a few days if I supply him the A-arms. Just need to order the Focus poly bushing kit now and have it shipped over.
Which ever way I go, I'll detail the specs and/or have a few kits made up.