Assuming the model numbers stayed the same for the next 10 years, here goes:

Model 35/70: boxlock nonejector, scalloped receiver, light scroll engraving
35/70E: Same gun with ejectors
74: like 35/70, but game scene engraving
74E: Same, with ejectors
76: Engraved sideplates
76E: Same, with ejectors

Those are the only Simson sxs models listed as of 1963. Hope that helps.