Well I finally got it home, once I got some time I tossed the plates back on it and was excited to take it out and start breaking in the motor but then... instant CEL and code for the knock sensor circuit. Since the RHD steering rack makes it even less accessible than the LHD one I had to pull the chassis brace, crossmember and exhaust off, just to be able to cram my hand up there enough to blindly unplug it. I muddled with the stock wiring a bit before realizing it was too damaged to use so instead of mucking with that I removed the plug and wiring from the spare non-turbo wiring harness I have and plugged that into the sensor and ECU and it *sort of* worked. Sort of meaning that while things were cool, it worked fine. But as soon as everything was up to temp, it would intermittently lose connection and throw a code, putting the car into limp mode until it was switched off and back on again.
That's a bit of an undignified way to get around, so I got some brand new shielded wire, disassembled the knock sensor plug and reassembled it with the new wire crimped into the old pin. I tried to do the same with an ECU pin but they're even more tightly crimped so I cheated and soldered it to a pin and a piece of wiring salvaged from the spare harness. Initial testing in my driveway threw no codes, today I'm hoping to take it for a drive and see if this has finally fixed the problem.
I also found a replacement black door, so I'll be able to get that taken care of as soon as I can pick it up.