1) Mirror the toolpath without reselecting geometry.
2) Reverse the toolpath so that the original climb cut/conventional cut strategy is maintained.
3) The mirrored toolpath must be verified against the mirrored geometry. 3D material removal is a requirement.
4) If looping is used in the original operation, the progression of the loops must be maintained in the mirrored toolpath. (If we start at the top and work down, the mirrored toolpath must progress in the same way.)
This video shows a quick solution to the problem while meeting the 4 objectives above.