Lots to know before you start. Are you going to fabricate your boxes or do you need to buy components? You may need to call around to the turbo kit folks to see if anyone has a fuel box set up for a kingkat
I built my kit for my first turbo setup and really enjoyed the experience. I learned a lot, but at a cost.
I think, I would be inclined to buy a used setup for another type of similar sled to get most of the basic components. Then you can start modifying/fabricating the sled specific stuff(air box, oil box).
You might also check with CPI and maybe OVS. They both used to turbo the 900 motor and may have some dusty components up on the shelf.
Please remember, first check on a fuel box. If its not available, that can almost shut down your project.