You need a 750 engine, the exhaust you want to use, exhaust hoses as needed, a fuel tank that fits (the stock tank fits unless you change things), a place to mount the electronics, a different impeller, ummm...
I am running a 750 engine, westcoast exhaust manifold from a 650 (has a different angle than the FPP manifold so it fits), FPP headpipe, SJ B-pipe chamber, SJ RN stock waterbox, Blaster exhaust outlet (ou the engine compartment side), misc hoses for the exhuast routing, a Kawi 550 fuel tank (going to change the tank), a few screws to mount the e-box to the stock water/fuel seperater and behind the fuel cover.
Everything else is from the 650.