After consulting with E3D, the only things that you need to upgrade are:
- Heat Sink
- A few cm of 1.75mm ID bowden tubing
I had the newer E3D Lite6, so the heater cartridge, thermistor, and heater block were all the same. While I originally tried to upgrade my Lite6 to a V6 by buying only those 3 parts, I badly damaged some parts trying to disassemble and reassemble my hotend. While trying to unassemble my LIte6, I deformed the heater block and was also unable to remove the thermistor and the nozzle. While trying to reassemble it into a V6, I bent the new heat brake.
After that disaster, I just decided to spend the money on a new E3D V6. It fits perfectly on the Wilson 2 without any redesign, I just had to recalibrate my z-offset. All in all, you could upgrade a Lite6 to a V6 for a minimal amount of money, but because mine was so tight and had so much residue I ended up braking it in the process and had to buy a new one.