Here is a picture of the new KA-52N cockpit and some technical information about this version. I have started some cockpit work two years ago, but there is so much new in this pit and I had no glue how to get all of this working.

https://thaimilitaryandasianregion.wordpress.com/2015/11/09/ka-52-alligator-attack-helicopters/

Same goes for the MI-28 but I think it's not as difficult as the KA-52. Ok we have to built a gunner pit for the MI-28, but the KA-52 seems more complex.

And here is the same about the MI-35:

https://thaimilitaryandasianregion.wordpress.com/2016/08/07/mi-35m-hind-e-attack-helicopters-russia/

I think upgrading them would be a big piece of work, but it's definitely worth it. We could still use the older versions for a Coldwar scenario.