Francesco:
I think you have the external tube shown as #1.519 on the picture. Or, if I remember correctly, there is also a tube under the side cover that carries oil through the pushrod gallery to the underside of the head which then feeds the other fitting I first talked about. The tube you show might be that one, or it they might be interchangable.
As for the pictures, those 2 came from the catalog for 'Chevs of the 40's' -
www.chevsofthe40s.com
I have a shop manual for a 1949 Chevrolet which has a complete section on the 216 engine, as well as an other old mechanics manuals