What is the meaning of "ΩK" on a wirewound resistor?
The "K" at the end is the tolerance value.  "K" is 10%.  The one marked 10ohms J is a 5% tolerance part.

Your 10 ohm K can be anywhere from 9 to 11 ohms.  The 10 ohm J part can be anywhere from 9.5 to 10.5 ohms.

You can find the tolerance codes in this wikipedia article on marking codes.



You are planning to replace a lower precision, lower wattage resistor with a higher precision higher wattage part.  That's fine.