Certainly, one could reduce normative language into purely logical-mathematical facts, if that was how one was using normative language.

Why do you talk of "language" so much? Suppose we didn't have language (and there was only ever a single person), I don't think the problem changes.

Would a reduction of 'ought' into purely mathematical statements ever connect up again to physics in a possible world?

Say, I would like to minimize ((X-2)*(X-2)+3)^^^3, where X is the number I'm going to observe on the screen. This is a pretty self-contained specification, and yet it refers to the world. The "logical" side of this can be regarded as a recipe, a symbolic representation of your goals. It also talks about a number that is too big to fit into the physical world.