Actually, the well worn mark above the fineness mark in the first box on the left is the assay office mark for Cairo. The three digits below it are the Arabic characters for 900. The center is indeed the lotus, in use from 1946 and indicates the item is silver. The last box is the date mark. We are currently researching the translation of stamped characters to formal Arabic lettering which is vastly different but based on what I have learned to this point is that this mark MIGHT indicate 1949. I use the word might since I have repeatedly been surprise with what is the actual answer. Does 1949 line up to your assumptions on the piece?
Currently, and understandably, I cannot reach my contacts at the Egyptian Assay Office but will inquire on the date mark for you as soon as I hear from them just to be sure. Until then, I may I hold on to your image as a point of reference?