Lamp driver sorted out, thanks to Barry! This overrides the low pressure warning light that was problematic.
I've been struggling to get copper washers for the proportioning valve outlets. They have a critical OD of 12.75mm. Ian had good access to get these fabricated; unfortunately I do not. So today I gave up, whipped out a file, and made them myself from standard washers. 90 minutes of non-stop fettling, and my fingers are agony. But, sorted! I've altered a part spec, reducing the specified banjo bolts from 20mm to 18mm to accommodate the thinner washers, and relieved the valve slightly, enabling me to get the rake I need on the pipe unions. As soon as the banjo bolts arrive, I'll have a brake pedal. Reminder to self: anneal washers.
Replacement vac pump arrived, and works just peachy, so I cut and filed the mounting lugs to enable fitting in the recess with appropriate brackets - again. Lovely to get most of it back together again. Another slight deviation from Ian's fit: - a 4-way plug for the vacuum electrics.
This one will get the ultimate test once finished, as it's due an MoT next week...