Glad to see another x-framer on here. It all depends on your budget and what you want to do with the car. I'd start with CPP (
http://www.classicperform.com) - they have everything for these cars to make them handle better on a budget. If you want to step up a notch, check out Global West (
http://globalwest.net/1958-64impala.html). Let me know if you have any other questions with regards to 58-64 full size Chevy's... I'm no authority but there's not a single component on mine that's stock
-Eric