Final update on the car - I’ll leave this thread up to assist others.
After much frustration with wiring, expensive bills that seemed never ending, it actually passed a VTNZ wof (which it then needed to fail for the cert...) and had cert booked.
However it wasn’t running well and struggling when VANOS kicked in. What I hadn’t realised was that this was due to the oil pickup gradually getting stuffed full of metal filings. Queue 2 big end bearings shot, one brand new oil pickup toast, non running engine and more bills to diagnose said engine I was over it.
I sold it from the workshop, never even got it back home.
Learnings? Rust is balls, and M52B28 engine would have been easier.