I got most of my parts from Alfashop in Norwich
My 164 is a 93 V6 24v on an L plate and I took it off the road 2 years ago,it needed a new clutch slave and master cylinders and I had problems sourcing a master cylinder at the time,so I bought and ran an Alfa 75 instead.
The two years it had been standing didn't do it any favours but I stuck at it and got my old 164 MOT'd last month.
Front lower wishbones,track rod ends,ball joints from Alfashop
Front and rear discs and pads from e bay
New front and rear calipers and flexi's
New centre exhaust section and rear box from E.B. Spares.
I replaced all the steel brake pipes with copper and replaced the timing belt
The clutch master cylinder is an 'experience' to replace
, but through determination is possible.You must use a proper flair wrench to undo the hydraulic union,I used an open ended spanner and it slipped,damaging the flats on the union but I was lucky enough to just get the flair wrench on it after.Dont be tempted to use an open ended spanner.It will slip.
A common corrosion area on the 164 is around the mounting points for the rear trailing arms,I had to get my local garage to weld them up.
The rear subframe is also a weak point for corrosion but mine had been replaced around 10 years ago so is OK.
The biggest problem I found was the availability of spares but if your prepared to wait then you should be OK.
Good luck!I remember being 11 years old and helping my father waxoyl and work on our Alfasud gold cloverleaf so hopefully your son should gain the same enjoyment and knowledge I did!