Mguner is correct, ball bearings are a luxury, they allow the turbo to spool up faster. The cool thing is you have a big block to spool those babies up. The question you have to ask yourself is this, what horsepower am I looking for. Then you have to decide are you going to use race gas or Pump. Intercooled or not. How much boost are you willing to give it. Believe it or not all these things need to align to properly size your turbo. You are right about the exhaust/turbine housing being to small will choke the motor and it will not make any top end power. Seeing how you have a 383 inch motor with a redline of 5500, I would say go with the .98 housings. It may spool up a little slower but this may save you grief in the traction department. Obviously you are considering twin turbo, there is so much to consider, so lets start by answering the questions above and I will try to get you an answer.