I will vouch for Paul at A4A, his attention to detail is meticulous but you do need to build a rpport with him. He is quiet and has never liked the quality of parts that GM started putting on later Alfas but he does know them well, and knows what to look for by seeing many examples over the years.
There is normally nearly always one of my cars in there at anyone time, in fact that sh1tty looking 155 outside is mine along with the turbo 4 pot out of it whihc is sat at the back of the garage in numerous different bits.