Another couple of significant steps forward today. I designed & printed a box / mounting for the battery cut-off switch in the engine bay & made off all the wire ends right round to the starter motor, so I now had 12v at the front of the car. I hooked up the ignition feed to that, so in theory there is now power throughout the car. I've stripped the binding off the looms from the bulkhead forward, so as I cut wires out of the system, I can re-bind it all neatly. I then moved some relays & re-connected some wiring & on turning the key, the low pressure fuel pump started. Having flooded the system, I then connected the high pressure pump & ran them both, with no leaks!
The exhaust is all-but finished, I need to fit a LAMBDA port & probably adjust the route a little, but the complex stuff is all done & I have an extra inch of ground clearance.