It looks like the certification issue is likely to be your problem.
I've checked the a/c that I thought most likely to meet CS27 Appendix B, the EC130B4 with dual hydraulics, SAS, two axis autopilot, etc. yet in the limitations section it still says 'The helicopter is approved to operate by day and night in VFR'.
I think it's probably right that the manufacturers can't be bothered to certify the a/c for IFR/IMC flight, even if the equipment fit would allow it, because there's no market for it.