The stock bottom end is pretty good for most applications. I personally don't trust anybody, so I did my rebuild myself. I would ask around your area for reccomendations for meticulous engine builders. Look at the mashine shop, is it unorganized and a shambles? Or is it clean and maintained? That says a lot about the kid of work they do. I would consider having SGP or JWT rebuild the motor. It costs more, but you knwo they will do an excellent job. Z1 motorsports may be someone to consider too. Why do you need to rebuild?