I would recommend just buying a new motor that is already built to handle a turbo that size. There are a lot of custom car shops that offer crate motors that are built to withstand up to 1000 hp, and arent too expensive. Rather than trying to build your exhisting motor up, I think it would be wise to buy a new one so you know your block is still good and its got quality parts on it. Also you will need to upgrade your tranny, cooling system, brakes, get full exhaust done, upgrade your fuel system, and do different gears in the car to withstand that much power.