K render over Carrstone brickwork section

Im going to be having my bungalow k rendered, there is however a section under the windows which have carrstone on it, which is popular in Norfolk.
Ive had a few quotes with a huge difference in all of them but I am being advised by some plasters that the carrstone needs to be removed and rebricked like the rest of the building and others are saying that the carrstone doesn't need to be removed and they can coat/prime the carrstone and the K render can then be applied.
Has anyone else K...

K render over Carrstone brickwork section