Andy , There is no bias bar. Getting the brake pedal "feel" right was a long, long battle! Originally fitted the Sierra donor master cylinder and could not get rid of the spongy feel. So then fitted a new Fiat 124 (19mm bore) Master cylinder with the remote fluid reservoir as in the pic. This resulted in too much pedal travel for my liking so reverted with a new Sierra master cylinder which eventually worked out OK. Had to bleed the system countless times to get it right. the front brakes are 260MM dia. discs with 60mm dia. caliper piston and drum rear brakes with std Sierra slave cylinders. There are no devices from the donor car in the brake lines. The IVA tester was well satisfied with the balance, with the fronts locking up first. On the way through I discarded the in-line hydraulic brake stop light switch and went for a mechanical switch operated off the brake foot pedal pushrod.
cheers John