Yes it is. Incidentally the only components that the shared between the K4 and KV6 are the liners. Every other component is different between the two engines.
It was the liners that made me ask as I remember being offered a FL1 2.5 V6 for £100 that had cracked/slipped/porous liners and a little bit of googling showed the same part for both engines, I didn't buy it but wish I had