Both of the below options look to be usable. They both have the correct 19.0mm or 3/4" bore. The first is an exact match and the second is only different in the shape and attachment of the reservoir.
Alfa Romeo GTV-6 - 1981-1985 Centric part# 136.02101 (Discontinued) (Exact Match)
Alfa Romeo Alfetta - 1975-1977 Centric part# 136.02100 (Reservoir is different)