I suspect that the "Torq Thrust" wheels were actually made by Halibrand (and copied by American Racing later). The same wheel is still available from Halibrand in limited sizes.
British Wire Wheel lists a 6" wheel for the 289, and while they say that it's Dayton and not Dunlop, we got some wheels that I'm pretty sure were Dunlop in 7" and 8" widths. See
this page , which has wheels made in special offsets for our FIA.