In view of recent posts, and the ensuing discussions, thought it might be useful to check out Locost_Oz group.

Found these details :-

"My wishbones are not a copy of the Westfield wishbones, but I think they are a distinct improvement on the book items. Firstly, the size of the wishbone tubes has been increased from 19mm by 1.6mm wall thickness, to 22mm by 2mm cold drawn seamless. The size of the shocker plate has been extended from 64mm to 125mm and from 128mm to 195mm ( have a look at the book wishbone diagram and you'll understand what that means)to extend the covered area between the two main arms. Also, there is a 22mm by 2mm crossbar running between the
two main arms just back from the inner bush tubes, which further increases torsional strength. The balljoint plate and the shocker plate are both laser cut 3mm plate. After a couple of prototypes this was the wishbone design and the size and type of steel that Chris Drabikowski from Ceedra Services finally tested and approved. While Ceedra Services was testing ICV's this wishbone was automatically approved, but you must check with other engineers before buying."