The 1866 law sounds unconstitutional anyway. Where is Congress granted the power to interfere with the workings of state legislatures? During that postwar time period when the radicals held sway, an awful lot of harm was done to the Constitutional form of government designed for the US by the framers of the USConstitution.
Why not repeal the 14th through 17th amendments? All four are antithetical to our originally designed form of government and all four have dubious ratification records as well.