This is an evolution of this mount: http://www.thingiverse.com/thing:846434 that fixes several shortcommings (distance of M3 screws etc.) and many other small improvements. I've also made a very nice fan duct for the 40mm stock fan!
With this mount the position and hight of the nozzle will stay the same as the stock one! For the extruder I bought a full metal version from Amazon and didn't re-use the stock parts.
I've recently designed a little cable holder as well - it is to secure the cables and give a strain relief.
If you want to use a second layer fan I've made a fan shroud for the second fan, have a look here: http://www.thingiverse.com/thing:1634657
I've printed all three parts in one print from ABS. For orientation of the parts please refer to the picture. Choose the thinest layer settings 0.15mm or better to ease finishing. There is no need for supports, all parts will print without any support!
The E3D hotend will press fit between the two parts. The best way is to press it with a bench vise, please put a thin metal pice in the gap so it will not break during pressing the parts together.
The fan duct will be clipped on the heat sink, there is no need for any screws. In my case it got a little crack when pushing it on the first time, but a drop of super glue fixed it and now it slides on the heat sink very smooth. You may need to drill the four holes with a 2.5mm drill as the first layer usually makes the holes smaller. The M3 screws for the fan will need no nuts, they just hold into the plastic. Make sure to only gently tighten these four screws!
You will need the following extra screws:
2x M3 x 30mm + 2x M3 nuts for the mount
4x M3 x 16mm for the fan
The mount will be slided on the original carrier (no need for modification) and fixed with the two screws from the front. You can remove the complete unit just by this two screws what eases maintenance.