MikeV,
I think what you are looking for used to be available( maybe now also). If my memory doesn't fail me, it is called a "vizier-sperre"( sight blocker).New England Custom Guns might be able to find one for you. If not, I agree with Ger that you should be able to make one. Sorry I don't have one to go by, but my drillings are scoped. BTW, I find my ELs very handy.
Mike