I am going to make my 1955 Bel Air a performance vehicle, this is what it has right now

straight 6 engine, upgrading to a performance 350
3-speed column shift trans

And everything else is stock for this set up, I figured I would have to beef up the rear end, put a different trans in, hoping to find a 3 speed out of a truck I can use. But what kind of things will I need to replace or upgrade to have a great performance running Bel Air? Like cooling, suspension, drivetrain, etc. Thanks for the advice.