Exhaust manifolds

Yup, put on a new manifold; it'll save you time-effort-money in the long run. Read this and this (replacing all the manifold studs while you've got everything apart is a very wise idea) and it is very much worth your while to get the good gaskets for the manifolds-to-head and intake-to-exhaust junctions. The new manifolds all have the '73-up type choke pocket. Address this and improve your choke setup by putting on one of the Electric choke kits. If your car + carb is a '73 or older, use a № 1231. If it's a '74-up, use a № 1234. If you're running a Super Six 2-barrel carb setup, use a № 1232.

The "flapper" (manifold heat control valve) needs to work properly, regardless of what kind of ignition you have and regardless of whether you live someplace warm or cold—unless your goals include poorer fuel economy, poorer driveability, and faster and worse oil contamination.