Oh, there you go, just had McLennans garage:
https://www.mclennansgarage.com/ (the other Fiat/Alfa specialist I mentioned) on the 'phone and he's talking again about wanting to properly examine the car before committing fully to a price but estimates the whole job at under £1,000 all in. He recons to include a head skim which would include a pressure test for cracking (Both these operations have to be done at a dedicated machine shop and are a good idea in my view), a change of engine oil and filter because water and other contaminants are likely to get in during the work also a cam belt kit including water pump. I don't know this garage quite so well as Kenny Harrison's but I believe he's an ex Alfa Romeo main dealer mechanic but I got "good vibes" speaking to him and he certainly sounded to me as if he knew exactly what he was talking about. He was astonished when I mentioned £500 to strip the head from the engine and give a firm quote.
So I think we can reliably say that either of these garages would do an A1 job for under £1000. Still a lot of money though isn't it but an awful lot less than your chaps up in Aberdeen are talking about.