Fixing the two problems were simple, once I figured out the how.
No.1 Indicators at the wrong height:
I made some small brackets and mounted the indicators up by 3cm. I was going to try jacking up the suspension again, but 3cm seemed a lot and making the bracket was a simple job and I didn't need to change the wiring.
The failure was more on the fact that at 3/4 lock the steering pulled to full lock (so opposite to self centring), which he rightly considered to be dangerous. I had to limit the lock to lock steering by adding steering limiters to the rack. This was easy; the hard part was making the car self centre. Lots of help from the forums and the advice was to increase the caster angle, but sadly that made no difference - I believe I had enough caster angle and increasing it didn't help. I checked and adjusted the camber angle, but still no self centring. I pumped the tyres up, but still nothing. And I knew that even though I had solved the anti-self centring, I need to show some degree of self centring for Mr. IVA.
I started to go down the route of wheel offset as the -21mm ER I had on my new wheels was quite different to the -38mm offset on the original Sierra wheels. Before I went too far down that route, I found that the one thing I thought I'd got roughly right was the Toe-in, but I discovered that my method of measurement was woeful! Armed with a laser, I re-measured the Toe in and discovered it was incorrect and needed 3 turns on the tie-rods to correct it to 0 degrees. A little more tyre pressure and I had self centring! Yes!
The re-test took 10 mins and cost me £90 - ouch.
I've now filled in all DVLA forms and posted it all off to our friends in Swansea - hoping for a swift (3 weeks) return before the sunshine disappears.