RS Products' new 300 series mount is pretty damn slick. He recently released pictures of a version designed for scopes, so if you don't mind waiting a bit for that launch then that may be your best bet.
Alternately, Midwest Industries makes a side mounted rail that is pretty long and would probably work well for putting your scope rings of choice on.
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"Throughout history, it has been the inaction of those who could have acted; the indifference of those who should have known better; the silence of the voice of justice when it mattered most; that has made it possible for evil to triumph."
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