Stock exhaust manifolds vs headers

Hey all,
I'm in the process of rebuilding the slant for my 66' dart, and am currently debating whether I should run headers or stay with the stock exhaust manifold. Currently the plans for the build include a 4bbl offy intake, 600 cfm Eddy carb, overbore pistons (machine shop has to assess damage to the bores then will give me a number), and a mild performance cam. My goals for the car is to be able to road trip, drive it on a somewhat regular basis, and be able to push it in the canyons on the weekends. Should I go with the stock manifold with a bigger pipe or go with some headers (Clifford most likely)?
I would go with headers, for sure. You also might want to consider raising the compression of your engine as well!