Mine started as a 08 600cfi, same chasis that you have, and now has a 700bb in it. Its a comparable swap. Depending on your plans for the 800 it is fairly simple.
There is a few decisions you need to make. First are you planning on running a single pipe or twin pipes?
I have used a Holz motor plate to do mine. I have a couple of the last remaining Holz plates and the instructions. Brad also makes a plate but its a little more difficult to install. It will drop the motor in the chasis though and gains you the twin pipe option. I will say this, I think I could still get twins in mine if I wanted to.
I would swith out the entire wiring harness to the new motor. I think you will have a much easier time.
Airbox fit.. well I have a turbo on mine so that was not an issue, I think you could easily retrofit a 600 carb airbox.
That leaves the fuel. You would have to remove the stock fuel pump and fit the tank for the carb fuel pump.
Its really not too bad of a swap.
