I have rebuilt my K8200 to use a 1.75mm E3D v6 hot end. Rather than rebuilding the original extruder and dealing with the issue of the non-standard hole distance I decided to print a well proven extruder design and make a new extruder plate for it. You can download the STL file here. Use an infill of 75%-80% to avoid flex. The very good extruder I printed is found here. I highly recommend it: http://www.thingiverse.com/thing:18379 The simple transparent plate that holds the hotend in place was bought from E3D together with the hotend. Should be easy enough to design. There ought to be an existing design somewhere already. The original fan of the E3D v6 looks good but sounds terrible. Such a small fan will always be noisy. There are very silent 40mm alternatives available. I printed all the fan holders for a 40mm fan and then selected the best one. This is it: http://www.thingiverse.com/thing:506958