This is about as good a screen used reference that I have. I just re-built my top mounts last week to the specs. of the top most scope mounts with the angled front and back and the two small holes at the bottom. They also have a dado to hug the barrel mounts as well.
These have always been the most difficult part of the ESB buildup and to this day still are.
Hope this pic helps a bit.
Steve 
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