Who sells KH calipers 4"

That's for real.

This is one of the reasons my car (factory KH Disc Brakes) was converted over to large bolt pattern.

LBP brake parts are easy to get and don't cost much.

Also.... My car sits allot... The KH set up does not like to sit (pistons stick). Make sure you get stainless pistons if you order new KN calipers.