This set is listed in the 1983 Games Workshop "Catalogue of Adventure", along with the first versions of SS1-4 and CP1 and 2. I have never seen it elsewhere. it is possible that the actual models were released in the c17 range as four of the August 1984 C17 Skeletons are shown by RAFM as BA19-22 "Heroes of Chaos" Skeleton Guardsman.
BA-19 Skeleton Guardsman of Chaos with spear
BA-20 Skeleton Guardsman of Chaos with sword & shield
BA-21 Skeleton Guardsman of Chaos with axe
BA-22 Skeleton Guardsman of Chaos- Guard Captain
C17 Skeletons - August 1984 Flyer