There are not really many holsters specifically made for the 3" K frames. Most are made for the 2.5" or 4" guns, so you have to decide whether you want a 1/2" of barrel sticking out or having 1" of extra leather hanging on your rig.
I ran into the same problem with my 3" J frame S&W. I ended up with an IWB holster from Don Hume which works pretty well. It is actually made for a 3" revolver. I also got a Fobus paddle rig too. It is really made for the 2" guns, but I don't mind a bit of barrel being exposed.
I guess it depends on what you are trying to accomplish with the rig. Is it for CCW carry or field carry? Do want a thumbsnap? Leather or plastic/kydex? Belt, IWB, SOB, ankle or shoulder holster....etc
There is the Bianchi "Shadow", which is a belt slide style holser with a thumbsnap on it, that is pretty good for strong side carry. Most of the holster companies have at least one to two offerings for K frames. I would check: DeSantis, Galco, Kramer, Milt Sparks, etc....