A 4" revolver is NO more difficult In my opinion to carry IWB than a 3" provided you have a good quality holster made for the gun, and a sturdy belt.
A K frame is also not difficult at all. I have no difficulty with a much larger revolver with just a T shirt for a cover garment, and I'm just an average size guy at 5'10 and 190ish. The key is a holster that holds the grip (hardest part to conceal) nice and tight to the body.
I actually find my longer barreled revolvers (4" and 5 1/2") more comfortable IWB than my snubby in a 3 o'clock position.
Pass on the chop job and spend that money on a really good holster.
I use Simply Rugged holsters my self with very good success.