Just to resume things and bring some conclusion... I bought replacement cooler for Alfa 75 3.0 12v. First impression is that this thing is way much lighter than original part (new cooler with fan mounted on weighs like dry old radiator).
Things are being cooled much faster, when fan kicks in he blows for much shorter time than it used to. Everything fits perfectly - no mods required. Thing is signed by "International radiators" and comes with two year warranty - good enough for me.
I'll see how it performs in summer, but no doubt - I believe it will be better. Price was 80 euro's.
Some pictures..
