You can get gaskets for this at TA I am sure but at this point I think I would put headers on it. Would be a nice Christmas present!
I was just wondering, picked up a set of non cracked manifolds for cheap. I refuse to pay $500 for headers that probably wont fit my car (85 regal) all that well, and for only a ~30hp gain. I will however, purchase them for my other motor once the heads come out, because I kinda have to. But for now, not in the cards. Manifolds suit me and my 211wrhp just fine.
If your new manifolds are not flat, you can try re-flattening them with a file. They warp enough over time to cause exhaust leaks. I filed the manifolds on my BBB 400, put them back on and problem solved. As soon as you hit it a couple times with the file it's easy to see where the problem areas are.
Stacey is correct. A good quality flat file for cast iron is a must. http://www.jkfilesandtools.com/right.html Quality tools, and proper knowledge are your friends.
Factory is cast iron to cast iron, no gasket. Manifolds are machined flat, as is the cylinder head mating surface. If the manifold needs .040 to flat it, you can bet that the head needs a similar amount of machining. If you don't machine the heads, definitely use good thick gaskets. A cast iron to cast iron seal will only work if both mating surfaces are perfect.
