Picked up another proportioning valve today from a Ford Laser at the wreckers.

Spoke to PBR who confirmed that there is no residual line pressure valve in the 180B dual circuit master, like the 1200 units and that it is all done in this valve assembley. Which is actually done on modern cars like Honda's, Hyundai etc etc

So will swap the units over tomorrow. Alot cheaper that the unit I was looking at from the brake specialist.