Sorry if you got a notification that there was another message, only to find it was deleted.  I uploaded a screengrab of the isoline display wire of the mesh, which wasn't showing the quad topology properly.  This is the final topology

I made the hole on the upper lip half the diameter it was before, and of course tapered the inner part of the larger holes:

I think this really brings the model much closer to the reference image. Should be as close as I can get without better reference. Now on to revise the screws... Then it's all done.

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