If it had been attacking the K the kashtans would have brought those missiles down at about 8-12km range.
The main difference would be that the old Soviet missiles fly low and fast all the way to the target so they are harder to detect... the best stealth puts the planet between you and your target.
Also only one Soviet missile would climb and scan for targets and then drop down to return to a sea skimming mode and process the data it collected and allocate targets to the other missiles attacking the group of ships. the distribution of missiles is determined by the lead missile based on the number of missiles in the group and the number of targets detected and their size.
BTW the ability of this US missile to fly around threat areas is interesting... especially assuming that new destroyers in the Russian Navy will have 400km range SAMs, so that is a circle 800km across it will need to fly around... quite a detour for a subsonic missile...
Would like to add that the Soviets and Russians take anti ship missiles very seriously and I really don't think 3-4 subsonic missiles would be enough to sink any Soviet ship above the size of a frigate... in the 1980s or now.