Without knowing either model in full, I would bet they headlight ears can be used in either model. My K1 has no indicator mount - the indicator stem is used to hold the headlight in place. But the difference in part number can be just because of the color.
K2 onwards had chrome headlight ears, therefore, the difference in part number can be because of the different location of the indicator mount. I would do this: check the upper and lower triple tree part number - if they are the same for K2 and K4, then the distance between upper and lower is the same, then the headlight ears must be compatible.