I think the Crane 2 will still work fine as a stabilising gimbal for the K-3, just like it would any camera/lens of the correct weight (maximum 3.2kg for the Crane 2, which should be OK for almost any K-3 + lens combo). It will keep the camera stable, and let you make basic adjustments yourself (point up, point down, rotate left/right etc) using the control buttons on the gimbal.
But some of the advanced bells-and-whistles (like the follow-focus feature) likely won't work because those features seem to be designed for specific Canon, Sony or Panasonic hardware.
Many of the gimbal bells and whistles will also depend on the Zhiyun Apple or Android app (ZyPlay) working OK on your tablet/phone.
For info, the Crane 2 manual is downloadable here:
http://zhiyundata.oss-cn-shenzhen.aliyuncs.com/zyplay/binary/instructions/in...0119164214.pdf