I'm currently taking a computer security module in University and as part of a problem have been asked:
My thought for the question is that no it does not provide 64 bits of security strength. This is as (IV,C) is transmitted over the network meaning that if the signal were intercepted by an adversary IV can easily be obtained as it has not been encrypted and hence is not confidential meaning that it doesn't add to the overall security. Rather 40 bits of security are enforced as K is not sent with the signal so the adversary cannot know K.
If anyone could comment on my answer or provide any alternative insight, it would be greatly appreciated.
NOTE: Edited answer to comment on how many bits I believe are actually enforced