Well, I am familar with the bust of saragon,which does look very africoid. Much of the sumerian art work though does not have very africoid features,but one bust of gudea does look very africoid. I am aware that the sumerians called their people sag gig whicvh means black headed people.I have talked to linguist who think the ancient sumerians are related to the dravidians of india and are working on a comparison of both tamil and sumerian lexicon.
I cannot not however agree with you that the sumerians were majority africoid. I am aware of the diversity of africoid people such as somalis,ethiopians,and even fulani having straight noses as oposed tomore convex nose.
I have also seen the bust of narma sin which indeed does look africoid. Do you have a picture of narma sin sphinx.