I have done a bit of further research on this matter.
It appears that the north koreans may indeed have had some
SU-85Ms in service, albeit telling apart a SU-85M from a SU-100 in an old pic
isn't a 100% thing.
If deemed worthwhile it could be included by adding a clone of unit 461 armed with weapon n. 90 85mm S-53 44, name change to SU-85M and increased ammo load to 48 rounds.