Whether or not you get an improvement from installing headers depends quite a bit on how restrictive the OEM manifolds were, as well as how much extra flow the exhaust can handle.
For headers, talk to the CAT folks, Rick at Sunbeam Specialties, or Dale Akuszewski at Dale’s restorations to see what fits your car and your budget. Getting them ceramic coated costs extra.
If you’re primarily looking to improve the appearance then talk to Sean "Moonstone" Ford (I think he’s with Caps Bright Coatings in California), about getting your stock manifolds ceramic-coated, inside and out. This will also help a little with heat dissipation.