I went down to the workshop today, and picked up the ECU and engine wiring loom (thanks, Scott!) - unfortunately, a couple of important parts have not arrived yet, so on Monday, I'll be cancelling the SVA appointment, and get one at the end of April (to give me enough time for the bits to arrive). As a result, I've taken the rest of the day off.
During the visit, John told me how I can get the rear section in a better alignment (it's something very obvious, and I missed it)! This should mean I on't need to worry too much about alignment pins.