Frillylily said:by both 'halves' you mean the branches, and the roots, correct?
I mean a cutting from the Black Walnut side and another cutting from the Golden Walnut side grafted onto a third walnut rootstock. I suggested taking a cutting from the original black walnut, even though it is a black walnut, because of the age of the tree.
Plants, all plants, are evolving slowly and the originals no longer look like what we have today. If the OP wants that original black walnut, they will have to taking a cutting of it from that tree.