Weaver Customer Service told me that a #58 one piece base will fit the model 56. Labeled for a model 57/57M it should work if the your (2) factory D&T'd mount holes measure 3.25" center to center. That base will require a standard Weaver style set of rings.
I have a Lyman #66MD aperture sight mounted on my Model 56 but have thought about playing around with a scope.