These days I favor L Frame guns over K Frames, but for carrying a K Frame IWB I use a Texas holster made by Adams Holsters. Excellent craftsmanship and great to do business with.
http://adamsholsters.com/store/
Old school gun; old school holster. I ran a 4" NY-1 model 64 for years in a surprise special by Elmer MacEvoy at the leather arsenal in Middleton, ID. Pretty much a summer special; unsurprising since Elmer started out under Milt. Still have the holster (works fine with a 3" 65-3), should have kept the NY-1. *Really* should have kept the NY-1.
Just a Hairy Special Snowflake supply clerk with no field experience, shooting an Asymetric carbine as a Try Hard. Snarky and easily butt hurt. Favorite animal is the Cape Buffalo....likely indicative of a personality disorder.
"If I had a grandpa, he would look like Delbert Belton".
Never carried a 4" K-frame IWB, but I've used a Bianchi Pistol Pocket to carry a 3" K- or L-frame a fair amount back in the early Aughties.