Look for Cordia or Tredia turbo parts - specifically the whole engine for a transplant. They are narrow block engines and will bolt directly to the transmission. The ECU is GARBAGE on these engines so swap it for a stand alone EMS like Megasquirt etc. The ECU's ran too lean (and did some other shady stuff too...) and caused exhaust manifolds to crack (this is the second issue you'll run into - finding a turbo manifold that hasn't got a crack in it) 'Bolting' a turbo onto a NA G63B is a less than ideal way to turbocharge it but you have easy options to upgrade it without a lot of work