It is very much worth your while to get the
good gaskets for the manifolds-to-head and intake-to-exhaust junctions.
Also, if you are still running the original exhaust manifold, be aware that the '70-'72 manifolds make extra hassles. Specifically, they have an open "stove" (hole directly into the inside of the manifold) at the top of the № 5 runner. This is sealed (kindasorta usually not very well) by a stamped sheetmetal cup that fits into the hole, with a (no longer available) gasket around its perimeter. On top of this cup is bolted the choke thermostat. If you are bound and determined to run this manifold, and there's any kind of a fault with or near the choke—doesn't work quite correctly, rod all tweaked and bent, rusty AF, exhaust leaks, etc—fabricate a blockoff plate and cut a suitable gasket for it, then plop a № 1231
electric choke kit on and be permanently done with choke problems.
But given that this manifold is warped and there's a high likelihood of cracks and/or heat control valve faults as well, unless you have no budget, you're best off installing a
carefully chosen new exhaust manifold.
Keep in mind that if you have the present manifold planed to address the warpage, its mount flanges will be thinner, which will mess with (lower) the force with which it is clamped to the head by the nuts and washers, and so future manifold-to-head gasket leaks will be more likely. If you try to end-run this by exceeding the specified torque, future manifold cracks become more likely.