The stock 4 cylinder Alfa lifter is 35mm.  The only place I personally have seen bigger Alfa lifters like you describe is in the F3 TS95 Nova Motors. Those I think have to be made ($).  My experience indicates that best 35mm lifters are the OEM ones that can easily be reconditioned at home.  You can also run a OEM Subaru lifter, or better yet a lightweight Supertech Subaru race lifter, however I have to have a DLC coating applied to make them last with most cams.  Call me if I can help.