[QUOTE=scottyo;12001291 The tops of the mounting holes are clean, but if you look closely, you can see the bottoms have some elongation wear (which seems a little odd to me).[/QUOTE]
If the tops of the mounting holes are good but the bottoms are not then I doubt that its been hogged out to fit badly placed bolt holes (unless they were drilled at some crazy angle!)
It looks more like the engine got very loose at one stage and the threaded shaft of the bolts acted like a rasp on the lower surface - just a guess as I got nothing else.