I used the Dvina which is the realistic SAM used in those scenarios.
Anyway, I will try the Volkhov to see if I have a better luck.
I manage to kill SR-71 with Dvina, but in previouse version of the SIM - (before realistic fuse settings). There are unclasified reports, that NVA manage to puncture SR-71 in one of his mission, so... We have the chance!