Actually that Argentinian head, that was floating around on slantsix.org, was a specially welded up version for one of there racing classes. Nicely done, but not a production piece.
the one you are thinking of was done up for Bonneville. the Argentinian head was bought buy someone on .org from somewhere in Argentina. the Bonneville head had a normal oval shaped chamber. the Argentinian head had a heart shaped chamber. two completely different heads.
