Are you planning on staying at 650 hp or are you thinking of adding power to the car? A 500 inch aluminum block engine can easily handle a lot more than 650 hp so you might only be a cam swap or head swap away from a lot more power.

Are you running a 9 inch rear? That makes it easier to swap gears and there are a lot more choices. It also gives you the ability to have a spare chuck all set up and ready to drop in.