Worth the headache?

Hey all. I have a 74 Dart with a 318. It has ps, pb, and a/c. The only mods I have planned are dual exhaust, eddy performer intake, and eddy 600 carb. With that combo what kind of horsepower would putting on some headers add? I'm trying to decide if it is worth the headache or the cash to get them installed at a shop. Lol. Thanks